If A + B + C = π, prove that
sin2 A – sin2 B + sin2 C = 2sin A cos B sin C
= sin2 A – sin2 B + sin2 C
Using formula ,
Using ,
since A + B + C = π
And sin(π – A) = sinA
Using , cos2A = 1 – 2sin2A
= 2sinAcosBsinC
= R.H.S