Triangle Calculator

a/sin(A) = b/sin(B) = c/sin(C). It relates each side to the sine of its opposite angle. Use it when you know an angle and the side opposite it, plus one more piece of information (AAS or SSA cases).

c² = a² + b² − 2ab·cos(C). It generalizes the Pythagorean theorem to all triangles. Use it for SSS (finding angles) or SAS (finding the third side). When C = 90°, it simplifies to the Pythagorean theorem.

Multiple methods: (1) Area = ½ × base × height. (2) Heron's formula with all three sides: Area = √(s(s−a)(s−b)(s−c)) where s is the semi-perimeter. (3) Two sides + included angle: Area = ½ab·sin(C).