Verify the identity. Sec x - sec x sin -x = cos x To verify the identity, start with the more complicated side and transform it to look like sec x - sec x sin x = sec x 1 - sin 2x) Factor out the greatest common factor, sec x. (Do not simplify.) = sec x( Apply a Pythagorean identity. Apply a reciprocal identity. Apply the appropriate even - odd identity. Apply a quotient identity