Trig Calculator

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Right Triangle Trigonometry Solver

Enter any two values (at least one side) to calculate all missing sides and angles.

Please enter at least two values, including at least one side length.

Results

Side A:
Side B:
Side C (Hypotenuse):
Angle A:
Angle B:
Area:
Perimeter:

Understanding Trigonometry Calculations

Trigonometry is the branch of mathematics dealing with the relationships between the sides and angles of triangles. For a right-angled triangle (where one angle is 90 degrees), we use specific ratios known as Sine, Cosine, and Tangent.

The Core Formulas (SOH CAH TOA)

Using Angle A as the reference point:

  • Sine (sin): Opposite / Hypotenuse (a / c)
  • Cosine (cos): Adjacent / Hypotenuse (b / c)
  • Tangent (tan): Opposite / Adjacent (a / b)
  • Pythagorean Theorem: a² + b² = c²

Common Trig Values

Angle (°) Sine (sin) Cosine (cos) Tangent (tan)
010
30°0.50.8660.577
45°0.7070.7071
60°0.8660.51.732
90°10Undefined

Real-World Example

Imagine you are leaning a 10-foot ladder against a wall. If the ladder makes a 60-degree angle with the ground, how high up the wall does it reach?

Given: Hypotenuse (c) = 10, Angle (A) = 60°.

Calculation: Side A = sin(60°) × 10 = 0.866 × 10 = 8.66 feet.

function solveTriangle() { var a = parseFloat(document.getElementById('sideA').value); var b = parseFloat(document.getElementById('sideB').value); var c = parseFloat(document.getElementById('sideC').value); var angleA = parseFloat(document.getElementById('angleA').value); var error = document.getElementById('errorMessage'); var results = document.getElementById('trigResults'); error.style.display = 'none'; results.style.display = 'none'; var count = 0; if (!isNaN(a)) count++; if (!isNaN(b)) count++; if (!isNaN(c)) count++; if (!isNaN(angleA)) count++; if (count = c) { error.innerHTML = "Hypotenuse must be longer than Side A"; error.style.display = "block"; return; } b = Math.sqrt(c * c – a * a); radA = Math.asin(a / c); angleA = radA * (180 / Math.PI); } else if (!isNaN(b) && !isNaN(c)) { if (b >= c) { error.innerHTML = "Hypotenuse must be longer than Side B"; error.style.display = "block"; return; } a = Math.sqrt(c * c – b * b); radA = Math.acos(b / c); angleA = radA * (180 / Math.PI); } // Case 2: One side and Angle A known else if (!isNaN(angleA)) { if (angleA = 90) { error.innerHTML = "Angle must be between 0 and 90 degrees"; error.style.display = "block"; return; } radA = angleA * (Math.PI / 180); if (!isNaN(a)) { c = a / Math.sin(radA); b = a / Math.tan(radA); } else if (!isNaN(b)) { a = b * Math.tan(radA); c = b / Math.cos(radA); } else if (!isNaN(c)) { a = c * Math.sin(radA); b = c * Math.cos(radA); } } var angleB = 90 – angleA; var area = 0.5 * a * b; var perimeter = a + b + c; document.getElementById('resSideA').innerText = a.toFixed(4); document.getElementById('resSideB').innerText = b.toFixed(4); document.getElementById('resSideC').innerText = c.toFixed(4); document.getElementById('resAngleA').innerText = angleA.toFixed(2) + "°"; document.getElementById('resAngleB').innerText = angleB.toFixed(2) + "°"; document.getElementById('resArea').innerText = area.toFixed(4); document.getElementById('resPerimeter').innerText = perimeter.toFixed(4); results.style.display = 'block'; } function resetTrigCalc() { document.getElementById('sideA').value = "; document.getElementById('sideB').value = "; document.getElementById('sideC').value = "; document.getElementById('angleA').value = "; document.getElementById('trigResults').style.display = 'none'; document.getElementById('errorMessage').style.display = 'none'; }

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