Question

Cos(π/4-x)cos(π/4-y)-sin(π/4-x)sin(π/4-y)=sin(x+y)

Answer 1

Step-by-step explanation:

CosAcosB- sinAsinB = cos(A-B) by appling this you will get LHS = cos (pie/2-(x+y) and then we know that cos(pie/2-x)=sinx thats why LHS = RHS = sin(x+y)