What is sin squared equal to?

Sin^(2)[X] = 1 - Cos^(2)[X]

It is based on Pythagorean theorem .

Algebraically rearrange

Sin^(2)[x] + Cos^(2)[X[ = 1^(2) = 1

Note how it looks like the Pythagorean triangle h^(2) = a^(2) + b^(2) .