22 Multiply then use fundamental identities to simplify the

22. Multiply; then use fundamental identities to simplify the expression below and determine which of the following is not equivalent. (2-2 cos X 2 cos x A) 4 Cos. x B) 4-4 COS X C) 4 Sin x D) csc X 1 cot

Solution

(2 - 2CosX)(2 + 2CosX)

=4 - 4Cos²X

= 4(1 - Cos²X)

Using identity Sin²X + Cos²X = 1 or 1 - Cos²X = Sin²X

4(1 - Cos²X) = 4Sin²X

Answer is C