1. The problem statement, all variables and given/known data Simplify cos^2 8x - sin^2x 2. Relevant equations 3. The attempt at a solution I thought it would be in the format of cos2x But I can't seem to figure it out I tried cos (4 * 2x) And I tried to change the sin^2x into 1-cos^2x and I could get any farther. Not sure how else to simplify.