Question

Explain why you cannot square each side of the equation when verifying a trigonometric identity.

Answer 1

This is because when we do verification of an identity, we must work separately on both sides, and to see in the end if we can get an equality. Because if we square both sides, that already means that we assume that the equality exist in the beginning, so no need to verify the identity. 

Answer 2

Answer:

While we are proving or verifying a trigonometric identity, we do not need to square each side of the equation.

This is so because if we are squaring each side of the equation, It means that the identity already exists and there is nothing to prove then.

So, we can only take one side and manipulate it or solve in such a way to reach a expression which is equivalent to the other. But we cannot square the  both sides simultaneously because we don't know whether the identity holds or not, We are just verifying it whether it is true or not.

Hence, If we square each side of the equation then there is no use of proving or verifying the identity,