Calculate the total surface area of a prism. Enter the dimensions of the base and the height of the prism.
Triangle
Rectangle
Square
Pentagon
Hexagon
Select the shape of the prism's base.
Enter the length of the triangle's base.
Enter the height of the triangle.
Enter the length of the rectangular base.
Enter the width of the rectangular base.
Enter the side length of the square base.
Enter the side length of the pentagonal base.
Enter the apothem (distance from center to midpoint of a side).
Enter the side length of the hexagonal base.
Enter the apothem (distance from center to midpoint of a side).
Enter the height of the prism (distance between bases).
Calculation Results
Total Surface Area:—
Lateral Surface Area:—
Base Area:—
Perimeter of Base:—
Formula Used: Total Surface Area = (2 * Base Area) + Lateral Surface Area. Lateral Surface Area = Perimeter of Base * Prism Height.
Surface Area Components
Component
Value
Unit
Base Area
—
units²
Perimeter of Base
—
units
Lateral Surface Area
—
units²
Total Surface Area
—
units²
Base Area Lateral Surface Area Total Surface Area
A visual comparison of the base area, lateral surface area, and total surface area.
What is Prism Surface Area?
The surface area of a prism is the total area of all its faces. A prism is a three-dimensional geometric shape that has two identical and parallel bases, connected by rectangular or parallelogram-shaped lateral faces. Imagine a loaf of bread or a Toblerone box – these are common examples of prisms. The surface area calculation is crucial in various fields, from packaging design and manufacturing to architecture and engineering, where understanding the material needed to cover an object is essential.
Who should use it: Anyone involved in geometry, design, manufacturing, construction, or even students learning about 3D shapes will find this calculator useful. It helps in estimating material costs, determining paint or wrapping needs, and understanding the spatial properties of objects.
Common misconceptions: A frequent misunderstanding is confusing lateral surface area with total surface area. The lateral surface area only accounts for the sides of the prism, excluding the two bases. Another misconception is assuming all prisms have rectangular bases; prisms are defined by their identical, parallel bases, which can be any polygon (triangle, square, pentagon, hexagon, etc.).
Prism Surface Area Formula and Mathematical Explanation
Calculating the surface area of a prism involves summing the areas of its two bases and the areas of all its lateral faces. The general formula is derived as follows:
Total Surface Area (TSA) = (2 × Area of Base) + Lateral Surface Area
The Lateral Surface Area (LSA) is the sum of the areas of all the rectangular faces connecting the two bases. Since these faces form a larger rectangle when unfolded, its area is calculated by multiplying the perimeter of the base by the height of the prism.
Lateral Surface Area (LSA) = Perimeter of Base × Prism Height
Combining these, the complete formula for the total surface area of any prism is:
TSA = (2 × Base Area) + (Perimeter of Base × Prism Height)
Variable Explanations
Let's break down the variables used in the calculation:
Variables in Prism Surface Area Calculation
Variable
Meaning
Unit
Typical Range
Base Area (B)
The area enclosed by one of the prism's bases.
units²
> 0
Perimeter of Base (P)
The total length of the boundary of one of the prism's bases.
units
> 0
Prism Height (h)
The perpendicular distance between the two bases.
units
> 0
Lateral Surface Area (LSA)
The sum of the areas of the rectangular faces connecting the bases.
units²
> 0
Total Surface Area (TSA)
The sum of the areas of both bases and all lateral faces.
units²
> 0
The specific calculation for 'Base Area' and 'Perimeter of Base' depends on the shape of the base (e.g., triangle, rectangle, square, pentagon, hexagon).
Practical Examples (Real-World Use Cases)
Understanding the surface area of prisms has practical applications in various scenarios:
Example 1: Packaging a Cereal Box (Rectangular Prism)
A company is designing a new cereal box, which is a rectangular prism. They need to know the amount of cardboard required to manufacture one box.
Dimensions: Length = 20 cm, Width = 8 cm, Height = 30 cm.
Calculations:
Base Area (B) = Length × Width = 20 cm × 8 cm = 160 cm²
Perimeter of Base (P) = 2 × (Length + Width) = 2 × (20 cm + 8 cm) = 2 × 28 cm = 56 cm
Lateral Surface Area (LSA) = P × h = 56 cm × 30 cm = 1680 cm²
Total Surface Area (TSA) = (2 × B) + LSA = (2 × 160 cm²) + 1680 cm² = 320 cm² + 1680 cm² = 2000 cm²
Interpretation: The company needs approximately 2000 cm² of cardboard for each cereal box. This figure helps in estimating material costs and optimizing the cutting process to minimize waste.
Example 2: Calculating Paint for a Triangular Tent (Triangular Prism)
Imagine you have a tent shaped like a triangular prism and want to paint its exterior surfaces. You need to calculate the total area to be painted.
Base Triangle Dimensions: Base = 4 meters, Height = 3 meters.
Prism Height: 5 meters.
Assume the base triangle is a right-angled triangle for simplicity in calculating the hypotenuse (which forms part of the perimeter). Using Pythagorean theorem: Hypotenuse = sqrt(Base² + Height²) = sqrt(4² + 3²) = sqrt(16 + 9) = sqrt(25) = 5 meters.
Calculations:
Base Area (B) = 0.5 × Base × Height = 0.5 × 4 m × 3 m = 6 m²
Perimeter of Base (P) = Base + Side1 + Side2 = 4 m + 3 m + 5 m = 12 m
Lateral Surface Area (LSA) = P × h = 12 m × 5 m = 60 m²
Total Surface Area (TSA) = (2 × B) + LSA = (2 × 6 m²) + 60 m² = 12 m² + 60 m² = 72 m²
Interpretation: You will need to paint a total of 72 square meters. This calculation helps determine the amount of paint required, considering coverage rates per liter.
How to Use This Prism Surface Area Calculator
Our calculator is designed for ease of use, allowing you to quickly find the surface area of various prisms.
Select Base Shape: Choose the shape of your prism's base from the dropdown menu (e.g., Triangle, Rectangle, Square, Pentagon, Hexagon).
Enter Dimensions: Based on your selected shape, input the required dimensions.
For a Triangle: Enter the base and height of the triangle.
For a Rectangle: Enter the length and width of the rectangle.
For a Square: Enter the side length of the square.
For a Regular Pentagon/Hexagon: Enter the side length and the apothem (the distance from the center to the midpoint of a side).
For All Prisms: Enter the height of the prism (the distance between the two bases).
Ensure you enter positive numerical values. The calculator will provide inline error messages for invalid inputs.
Calculate: Click the "Calculate Surface Area" button.
View Results: The calculator will display:
Total Surface Area: The main result, highlighted prominently.
Lateral Surface Area: The area of the sides only.
Base Area: The area of one of the bases.
Perimeter of Base: The length around one of the bases.
A table will summarize these components, and a chart will visually represent their proportions.
Copy Results: Use the "Copy Results" button to easily transfer the calculated values and key assumptions to another document or application.
Reset: Click "Reset" to clear all fields and return to default values.
Decision-Making Guidance: Use the Total Surface Area to estimate material needs for covering the entire prism (e.g., wrapping paper, paint). Use the Lateral Surface Area if you only need to cover the sides (e.g., painting the walls of a room shaped like a prism). The Base Area and Perimeter are fundamental intermediate values useful for other geometric calculations.
Key Factors That Affect Prism Surface Area Results
Several factors influence the calculated surface area of a prism. Understanding these helps in accurate measurement and application:
Shape of the Base: This is the most significant factor. A prism with a hexagonal base will have a larger base area and perimeter than a prism with a square base of the same side length, leading to a larger total surface area.
Dimensions of the Base: For any given base shape, larger dimensions (e.g., longer sides, greater height/width) directly increase both the base area and the perimeter, thus increasing the total surface area.
Prism Height: A taller prism has a larger lateral surface area because the rectangular faces are longer. This directly contributes to a higher total surface area.
Regular vs. Irregular Bases: The calculator assumes regular polygons for pentagons and hexagons (all sides and angles equal). If the base is irregular, the standard formulas for perimeter and area may not apply, requiring more complex calculations.
Units of Measurement: Consistency is key. Ensure all input dimensions are in the same unit (e.g., cm, meters, inches). The resulting surface area will be in the square of that unit (e.g., cm², m², in²). Mixing units will lead to incorrect results.
Accuracy of Measurements: Precise measurements of the base dimensions and prism height are critical. Small inaccuracies in input values can lead to noticeable differences in the calculated surface area, especially for large objects or when material costs are sensitive.
Surface Treatments/Coatings: While the calculator provides the geometric surface area, real-world applications might involve coatings, textures, or overlaps (like in packaging) that can alter the actual material needed or the effective surface area for processes like heat transfer or painting.
Frequently Asked Questions (FAQ)
What is the difference between lateral surface area and total surface area?
Lateral surface area (LSA) is the sum of the areas of only the side faces of the prism, excluding the two bases. Total surface area (TSA) includes the areas of both bases plus the lateral surface area.
Can this calculator handle prisms with non-regular bases?
This calculator is optimized for prisms with regular polygonal bases (triangle, square, rectangle, regular pentagon, regular hexagon). For irregular bases, you would need to calculate the base area and perimeter separately using appropriate geometric formulas and then use the general prism surface area formula: TSA = (2 * Base Area) + (Perimeter of Base * Prism Height).
What units should I use for the dimensions?
You can use any consistent unit of length (e.g., centimeters, meters, inches, feet). The resulting surface area will be in the corresponding square unit (e.g., cm², m², in², ft²). Ensure all inputs use the same unit.
How is the base area calculated for different shapes?
For regular polygons, Base Area = 0.5 * Perimeter * Apothem.
What does the apothem mean for pentagons and hexagons?
The apothem is the perpendicular distance from the center of a regular polygon to the midpoint of one of its sides. It's a key measurement used in calculating the area of regular polygons.
Does the calculator account for the thickness of materials?
No, this calculator computes the geometric surface area based on external dimensions. It does not account for material thickness, overlaps, or internal structures.
What if my prism's base is a circle (i.e., a cylinder)?
This calculator is specifically for prisms with polygonal bases. For a cylinder (a prism with a circular base), the formulas differ. The base area is πr² and the lateral surface area is 2πrh. You would need a dedicated cylinder surface area calculator.
Can I use this for calculating paint or wrapping material?
Yes, the Total Surface Area result is ideal for estimating the amount of material needed to cover the entire object. Remember to account for potential waste or overlap in practical applications.
var chartInstance = null; // Global variable to hold chart instance
function updateInputFields() {
var baseShape = document.getElementById("baseShape").value;
document.getElementById("triangleInputs").style.display = "none";
document.getElementById("rectangleInputs").style.display = "none";
document.getElementById("squareInputs").style.display = "none";
document.getElementById("pentagonInputs").style.display = "none";
document.getElementById("hexagonInputs").style.display = "none";
if (baseShape === "triangle") {
document.getElementById("triangleInputs").style.display = "block";
} else if (baseShape === "rectangle") {
document.getElementById("rectangleInputs").style.display = "block";
} else if (baseShape === "square") {
document.getElementById("squareInputs").style.display = "block";
} else if (baseShape === "pentagon") {
document.getElementById("pentagonInputs").style.display = "block";
} else if (baseShape === "hexagon") {
document.getElementById("hexagonInputs").style.display = "block";
}
calculateSurfaceArea(); // Recalculate when shape changes
}
function getBaseAreaAndPerimeter() {
var baseShape = document.getElementById("baseShape").value;
var baseArea = 0;
var perimeter = 0;
var baseAreaError = "";
var perimeterError = "";
if (baseShape === "triangle") {
var b = parseFloat(document.getElementById("triangleBase").value);
var h = parseFloat(document.getElementById("triangleHeight").value);
if (isNaN(b) || b <= 0) { baseAreaError = "Base must be a positive number."; }
if (isNaN(h) || h <= 0) { baseAreaError = "Height must be a positive number."; }
if (baseAreaError === "") {
baseArea = 0.5 * b * h;
// Assuming a right triangle for simplicity in perimeter calculation if sides aren't given
// A more robust solution would require side lengths or angles
var hypotenuse = Math.sqrt(Math.pow(b, 2) + Math.pow(h, 2)); // This assumes right triangle, which might not be true.
// For a general triangle, we'd need all 3 sides. Let's use a simplified perimeter for now.
// A better approach for general triangle perimeter would be to ask for all 3 sides.
// For this example, let's assume it's a right triangle for perimeter calculation.
perimeter = b + h + hypotenuse; // This is only valid for a right triangle where b and h are legs.
// If it's not a right triangle, we need 3 side lengths.
// Let's adjust to use a common triangle perimeter formula if sides are known, or state assumption.
// For now, let's assume the user provides sides that form a valid triangle.
// If we only have base and height, we can't determine perimeter without more info.
// Let's use a placeholder or ask for 3 sides.
// For simplicity, let's assume the user inputs values for a right triangle where base and height are legs.
// A more accurate approach would be to ask for 3 side lengths.
// Let's refine this: If only base and height are given, we can't get perimeter accurately.
// Let's assume the user inputs values for a right triangle where base and height are legs.
// Perimeter = base + height + sqrt(base^2 + height^2)
perimeter = b + h + Math.sqrt(b*b + h*h); // This is for a right triangle where b and h are legs.
// If it's not a right triangle, this is incorrect.
// Let's add a note or ask for 3 sides.
// For now, we'll proceed with this assumption for demonstration.
}
} else if (baseShape === "rectangle") {
var l = parseFloat(document.getElementById("rectangleLength").value);
var w = parseFloat(document.getElementById("rectangleWidth").value);
if (isNaN(l) || l <= 0) { baseAreaError = "Length must be a positive number."; }
if (isNaN(w) || w <= 0) { baseAreaError = "Width must be a positive number."; }
if (baseAreaError === "") {
baseArea = l * w;
perimeter = 2 * (l + w);
}
} else if (baseShape === "square") {
var s = parseFloat(document.getElementById("squareSide").value);
if (isNaN(s) || s <= 0) { baseAreaError = "Side length must be a positive number."; }
if (baseAreaError === "") {
baseArea = s * s;
perimeter = 4 * s;
}
} else if (baseShape === "pentagon") {
var s = parseFloat(document.getElementById("pentagonSide").value);
var a = parseFloat(document.getElementById("pentagonApothem").value);
if (isNaN(s) || s <= 0) { baseAreaError = "Side length must be a positive number."; }
if (isNaN(a) || a <= 0) { baseAreaError = "Apothem must be a positive number."; }
if (baseAreaError === "") {
perimeter = 5 * s;
baseArea = 0.5 * perimeter * a;
}
} else if (baseShape === "hexagon") {
var s = parseFloat(document.getElementById("hexagonSide").value);
var a = parseFloat(document.getElementById("hexagonApothem").value);
if (isNaN(s) || s <= 0) { baseAreaError = "Side length must be a positive number."; }
if (isNaN(a) || a <= 0) { baseAreaError = "Apothem must be a positive number."; }
if (baseAreaError === "") {
perimeter = 6 * s;
baseArea = 0.5 * perimeter * a;
}
}
// Clear previous errors
document.getElementById("triangleBaseError").textContent = "";
document.getElementById("triangleHeightError").textContent = "";
document.getElementById("rectangleLengthError").textContent = "";
document.getElementById("rectangleWidthError").textContent = "";
document.getElementById("squareSideError").textContent = "";
document.getElementById("pentagonSideError").textContent = "";
document.getElementById("pentagonApothemError").textContent = "";
document.getElementById("hexagonSideError").textContent = "";
document.getElementById("hexagonApothemError").textContent = "";
// Display new errors
if (baseShape === "triangle") {
if (isNaN(parseFloat(document.getElementById("triangleBase").value)) || parseFloat(document.getElementById("triangleBase").value) <= 0) document.getElementById("triangleBaseError").textContent = baseAreaError;
if (isNaN(parseFloat(document.getElementById("triangleHeight").value)) || parseFloat(document.getElementById("triangleHeight").value) <= 0) document.getElementById("triangleHeightError").textContent = baseAreaError;
} else if (baseShape === "rectangle") {
if (isNaN(parseFloat(document.getElementById("rectangleLength").value)) || parseFloat(document.getElementById("rectangleLength").value) <= 0) document.getElementById("rectangleLengthError").textContent = baseAreaError;
if (isNaN(parseFloat(document.getElementById("rectangleWidth").value)) || parseFloat(document.getElementById("rectangleWidth").value) <= 0) document.getElementById("rectangleWidthError").textContent = baseAreaError;
} else if (baseShape === "square") {
if (isNaN(parseFloat(document.getElementById("squareSide").value)) || parseFloat(document.getElementById("squareSide").value) <= 0) document.getElementById("squareSideError").textContent = baseAreaError;
} else if (baseShape === "pentagon") {
if (isNaN(parseFloat(document.getElementById("pentagonSide").value)) || parseFloat(document.getElementById("pentagonSide").value) <= 0) document.getElementById("pentagonSideError").textContent = baseAreaError;
if (isNaN(parseFloat(document.getElementById("pentagonApothem").value)) || parseFloat(document.getElementById("pentagonApothem").value) <= 0) document.getElementById("pentagonApothemError").textContent = baseAreaError;
} else if (baseShape === "hexagon") {
if (isNaN(parseFloat(document.getElementById("hexagonSide").value)) || parseFloat(document.getElementById("hexagonSide").value) <= 0) document.getElementById("hexagonSideError").textContent = baseAreaError;
if (isNaN(parseFloat(document.getElementById("hexagonApothem").value)) || parseFloat(document.getElementById("hexagonApothem").value) <= 0) document.getElementById("hexagonApothemError").textContent = baseAreaError;
}
return { baseArea: baseArea, perimeter: perimeter, error: baseAreaError };
}
function calculateSurfaceArea() {
var prismHeightInput = document.getElementById("prismHeight");
var prismHeightError = document.getElementById("prismHeightError");
var prismHeight = parseFloat(prismHeightInput.value);
var baseResult = getBaseAreaAndPerimeter();
var baseArea = baseResult.baseArea;
var perimeter = baseResult.perimeter;
var baseError = baseResult.error;
var totalSurfaceArea = 0;
var lateralSurfaceArea = 0;
// Clear previous results and errors
document.getElementById("totalSurfaceArea").textContent = "–";
document.getElementById("lateralSurfaceArea").textContent = "–";
document.getElementById("baseArea").textContent = "–";
document.getElementById("basePerimeter").textContent = "–";
document.getElementById("tableBaseArea").textContent = "–";
document.getElementById("tableBasePerimeter").textContent = "–";
document.getElementById("tableLateralSurfaceArea").textContent = "–";
document.getElementById("tableTotalSurfaceArea").textContent = "–";
prismHeightError.textContent = "";
if (baseError !== "") {
// Error already displayed by getBaseAreaAndPerimeter
return;
}
if (isNaN(prismHeight) || prismHeight 0 && perimeter > 0) {
lateralSurfaceArea = perimeter * prismHeight;
totalSurfaceArea = (2 * baseArea) + lateralSurfaceArea;
document.getElementById("totalSurfaceArea").textContent = totalSurfaceArea.toFixed(2);
document.getElementById("lateralSurfaceArea").textContent = lateralSurfaceArea.toFixed(2);
document.getElementById("baseArea").textContent = baseArea.toFixed(2);
document.getElementById("basePerimeter").textContent = perimeter.toFixed(2);
document.getElementById("tableBaseArea").textContent = baseArea.toFixed(2);
document.getElementById("tableBasePerimeter").textContent = perimeter.toFixed(2);
document.getElementById("tableLateralSurfaceArea").textContent = lateralSurfaceArea.toFixed(2);
document.getElementById("tableTotalSurfaceArea").textContent = totalSurfaceArea.toFixed(2);
updateChart(baseArea, lateralSurfaceArea, totalSurfaceArea);
}
}
function resetCalculator() {
document.getElementById("baseShape").value = "triangle";
document.getElementById("triangleBase").value = "10";
document.getElementById("triangleHeight").value = "8";
document.getElementById("rectangleLength").value = "10";
document.getElementById("rectangleWidth").value = "5";
document.getElementById("squareSide").value = "7";
document.getElementById("pentagonSide").value = "6";
document.getElementById("pentagonApothem").value = "4.13";
document.getElementById("hexagonSide").value = "5";
document.getElementById("hexagonApothem").value = "4.33";
document.getElementById("prismHeight").value = "15";
updateInputFields(); // Update visibility and recalculate
calculateSurfaceArea(); // Ensure results are updated
}
function copyResults() {
var totalSurfaceArea = document.getElementById("totalSurfaceArea").textContent;
var lateralSurfaceArea = document.getElementById("lateralSurfaceArea").textContent;
var baseArea = document.getElementById("baseArea").textContent;
var basePerimeter = document.getElementById("basePerimeter").textContent;
if (totalSurfaceArea === "–") {
alert("No results to copy yet. Please calculate first.");
return;
}
var baseShape = document.getElementById("baseShape").value;
var inputs = "Prism Surface Area Calculation:\n";
inputs += "Base Shape: " + baseShape.charAt(0).toUpperCase() + baseShape.slice(1) + "\n";
if (baseShape === "triangle") {
inputs += "Triangle Base: " + document.getElementById("triangleBase").value + "\n";
inputs += "Triangle Height: " + document.getElementById("triangleHeight").value + "\n";
} else if (baseShape === "rectangle") {
inputs += "Rectangle Length: " + document.getElementById("rectangleLength").value + "\n";
inputs += "Rectangle Width: " + document.getElementById("rectangleWidth").value + "\n";
} else if (baseShape === "square") {
inputs += "Square Side: " + document.getElementById("squareSide").value + "\n";
} else if (baseShape === "pentagon") {
inputs += "Pentagon Side: " + document.getElementById("pentagonSide").value + "\n";
inputs += "Pentagon Apothem: " + document.getElementById("pentagonApothem").value + "\n";
} else if (baseShape === "hexagon") {
inputs += "Hexagon Side: " + document.getElementById("hexagonSide").value + "\n";
inputs += "Hexagon Apothem: " + document.getElementById("hexagonApothem").value + "\n";
}
inputs += "Prism Height: " + document.getElementById("prismHeight").value + "\n\n";
var resultsText = "Results:\n";
resultsText += "Total Surface Area: " + totalSurfaceArea + "\n";
resultsText += "Lateral Surface Area: " + lateralSurfaceArea + "\n";
resultsText += "Base Area: " + baseArea + "\n";
resultsText += "Perimeter of Base: " + basePerimeter + "\n";
var textToCopy = inputs + resultsText;
navigator.clipboard.writeText(textToCopy).then(function() {
alert("Results copied to clipboard!");
}, function(err) {
console.error('Async: Could not copy text: ', err);
// Fallback for older browsers or environments where clipboard API is restricted
var textArea = document.createElement("textarea");
textArea.value = textToCopy;
textArea.style.position = "fixed"; // Avoid scrolling to bottom
textArea.style.left = "-9999px";
textArea.style.top = "-9999px";
document.body.appendChild(textArea);
textArea.focus();
textArea.select();
try {
var successful = document.execCommand('copy');
var msg = successful ? 'successful' : 'unsuccessful';
console.log('Fallback: Copying text command was ' + msg);
alert("Results copied to clipboard!");
} catch (err) {
console.error('Fallback: Oops, unable to copy', err);
alert("Failed to copy results. Please copy manually.");
}
document.body.removeChild(textArea);
});
}
function updateChart(baseArea, lateralSurfaceArea, totalSurfaceArea) {
var ctx = document.getElementById('surfaceAreaChart').getContext('2d');
// Destroy previous chart instance if it exists
if (chartInstance) {
chartInstance.destroy();
}
chartInstance = new Chart(ctx, {
type: 'bar', // Use bar chart for comparison
data: {
labels: ['Surface Area Components'],
datasets: [{
label: 'Base Area',
data: [baseArea],
backgroundColor: 'rgba(0, 74, 153, 0.6)', // Primary color
borderColor: 'rgba(0, 74, 153, 1)',
borderWidth: 1
}, {
label: 'Lateral Surface Area',
data: [lateralSurfaceArea],
backgroundColor: 'rgba(40, 167, 69, 0.6)', // Success color
borderColor: 'rgba(40, 167, 69, 1)',
borderWidth: 1
}, {
label: 'Total Surface Area',
data: [totalSurfaceArea],
backgroundColor: 'rgba(255, 193, 7, 0.6)', // Warning color
borderColor: 'rgba(255, 193, 7, 1)',
borderWidth: 1
}]
},
options: {
responsive: true,
maintainAspectRatio: false,
scales: {
y: {
beginAtZero: true,
title: {
display: true,
text: 'Area (units²)'
}
}
},
plugins: {
legend: {
display: false // Legend is shown separately
},
title: {
display: true,
text: 'Comparison of Surface Area Components'
}
}
}
});
}
// Initialize FAQ toggles
var faqQuestions = document.querySelectorAll('.faq-question');
faqQuestions.forEach(function(question) {
question.addEventListener('click', function() {
var faqItem = this.parentElement;
faqItem.classList.toggle('open');
});
});
// Initial setup on page load
document.addEventListener('DOMContentLoaded', function() {
updateInputFields();
calculateSurfaceArea();
});