Question

sin(A+B) + sin(A-B)=2sinA cos B
prove identity..

Answer 1

:O

Answer 2

Okay i am good at math but this just confuses me

Answer 3

I found that on the Internet, I hope this can help you.

sin(a + b) + sin(a - b) = 2sin(a)cos(b)
LHS = sin(a + b) + sin(a - b)
using the sum formula for sine
LHS = sin(a)cos(b) + cos(a)sin(b) + sin(a)cos(b) - cos(a)sin(b)
LHS = sin(a)cos(b) + sin(a)cos(b) + [cos(a)sin(b) - cos(a)sin(b)]
LHS = 2sin(a)cos(b) + ( 0 )
LHS = 2sin(a)cos(b)
RHS = 2sin(a)cos(b)
therefore, LHS = RHS

Answer 4

@y1066380 , thank you!