Triangle Calculator

Solve any triangle. Enter any 3 values (at least one side) to find all angles, sides, area, perimeter, and more.

Enter Known Values

Sides: a, b, c — Angles: A (opposite a), B (opposite b), C (opposite c). Enter at least 3 values including one side.

Side a

Side b

Side c

Angle A (°)

Angle B (°)

Angle C (°)

Solution

Property	Value

Triangle Solving Methods

a² + b² = c² where c is the hypotenuse (side opposite the 90° angle).

c² = a² + b² − 2ab·cos(C). Used when you know SSS or SAS.

a/sin(A) = b/sin(B) = c/sin(C). Used when you know ASA, AAS, or SSA.

s = (a+b+c)/2 (semi-perimeter), Area = √(s(s−a)(s−b)(s−c))