Triangle Calculator
Solve any triangle - find missing sides, angles, area and perimeter using Law of Cosines and Law of Sines.
About Triangle Calculator
Enter any 3 known values (at least one side) — the calculator finds the remaining sides and angles using Law of Sines (a/sinA = b/sinB = c/sinC) and Law of Cosines (c² = a² + b² - 2ab·cos C). Area uses Heron's formula: A = √(s(s-a)(s-b)(s-c)) where s = (a+b+c)/2.
Triangle Values
Enter 3 values (at least one side). Leave others as 0.
Side a
Side b
Side c
Angle A (°)
Angle B (°)
Angle C (°)
Results
Side a
3
Side b
4
Side c
5
Angle A
36.87°
Angle B
53.13°
Angle C
90°
Area
6
Perimeter
12
Right triangle with sides 3, 4, 5 has area 6 and perimeter 12.