Question 195762
Identity # 1: sin(A + B) = sin(A)cos(B) + cos(A)sin(B)




Identity # 2: sin(A - B) = sin(A)cos(B) - cos(A)sin(B)




Subtract equations:



sin(A + B) - sin(A - B) = (sin(A)cos(B) - sin(A)cos(B)) + (cos(A)sin(B) -(- cos(A)sin(B)) ) 



sin(A + B) - sin(A - B) = 2cos(A)sin(B)  



1/2[ sin(A + B) - sin(A - B) ] = cos(A)sin(B) 




Answer:  cos(A)sin(B) = 1/2[ sin(A + B) - sin(A - B) ]