Question

find cos^2 45-sin^2 15

Answer 1

cos²45-sin²45
= (1/2)²-(1/2)²
= 1/4-1/4
=0

Answer 2

It is of the form (a+b)(a-b)
Therefore (cos 45+sin45)(cos45-sin45)
We know that cos 45=sin45
Therefore the equation derives to 0
Therefore the answer is 0