Triangle Calculator

Calculate area, perimeter, angles, and height of a triangle from its three sides. Automatically identifies triangle type.

Triangle Sides

Enter the length of all three sides

📐 Triangle Types

Equilateral

All sides equal, all angles 60°

Isosceles

Two sides equal, two angles equal

Scalene

All sides different lengths

Right

One angle is 90° (a² + b² = c²)

Acute

All angles less than 90°

Obtuse

One angle greater than 90°

📝 Formulas Used

Area (Heron's Formula)

s = (a + b + c) / 2
Area = √[s(s-a)(s-b)(s-c)]

Perimeter

P = a + b + c

Height

h = 2 × Area / base

Angles (Law of Cosines)

cos(A) = (b² + c² - a²) / (2bc)