Verify the identity StartFraction sine left parenthesis alph

Verify the identity.

StartFraction sine left parenthesis alpha plus beta right parenthesis Over sine alpha cosine beta EndFraction equals 1 plus cotangent alpha tangent beta

sin(+)

sincos

=1+cottan

Solution

sin(+)/sincos =1+cottan

sin( + ) = sin()cos() + cos()sin()

LHS ======> sin()cos()/sincos + cos()sin()/sincos = 1 + cot()*tan() = RHS