Question

prove that sin 45 = cos 45​

Answer 1

Answer:

sin(45+A).cos(45-B)+cos(45+A).sin(45-B)=cos(A-B).

L.H.S.

Let (45+A) =x ,and (45-B) = y.

= sin x.cos y+cos x.sin y

= sin ( x+y) , on putting the values of x and y.

= sin(45+A+45-B)

= sin{ 90 +(A-B) }

= cos ( A - B ) , proved.