Law of Cosines Explorer

Drag the triangle vertices to see how side lengths and angles affect the Law of Cosines calculations

Interactive Triangle

         Side a (opposite A)
        
         0.0

         Side b (opposite B)
        
         0.0

         Side c (opposite C)
        
         0.0

         Angle A
        
         0.0°

         Angle B
        
         0.0°

         Angle C
        
         0.0°

The Law of Cosines states:

a² = b² + c² − 2bc cos(A)

b² = a² + c² − 2ac cos(B)

c² = a² + b² − 2ab cos(C)

Calculate for:

The Law of Cosines relates the sides and angles of any triangle. When the angle is 90°, it reduces to the Pythagorean theorem (cos(90°) = 0)!