Question

Prove that :
Cos54.cos36 - sin45.sin36=0

The question seem to be tricky so i need help

Answer 1

hey..

i think it is not sin 45 it's sin 54
cos54.cos36 - sin54.sin36
cos36 = sin54
sin54 = cos36
cos54.sin54 - cos36.sin36
[email protected]@=1
1 - 1 = 0

hence proved