Right Triangle Calculator

Right Triangle – Quick Cheat Sheet

• Setup: ∠C = 90°. Legs: a opposite ∠A, b opposite ∠B. Hypotenuse: c.
• Pythagorean: a² + b² = c²
• SOH-CAH-TOA: sin A = a/c, cos A = b/c, tan A = a/b (and swap a,b for ∠B).
• Angles: A + B = 90°, A = arctan(a/b), B = arctan(b/a).
• Area: Area = (a·b)/2.   Perimeter: P = a + b + c.
• Inradius: r = (a + b - c)/2.   Circumradius: R = c/2.
• Altitude to hypotenuse: h = (a·b)/c. Projections: p = a²/c, q = b²/c, and p + q = c.
• Units: Inputs are unitless but consistent—if sides are in cm, results are in cm (areas in cm²).
• Degrees ↔ Radians: deg = rad × 180/π, rad = deg × π/180.