Question

Given A = 60° and B = 30°,
prove that : sin (A + B) = sin A cos B + cos A sin B

Answer 1

Given A = 60° and B = 30°

LHS = sin(A + B)
= sin (60° + 30°)
= sin 90°
= 1

RHS = sin A cos B + cos A sin B
= sin 60° cos 30° + cos 60° sin 30°

= `(sqrt3)/(2) (sqrt3)/(2) + (1)/(2) (1)/(2)`

= `(3)/(4) + (1)/(4)`

= 1
LHS = RHS