Verify the identity cos 7x 7y cos 7x 7y 2 cos 7x cos 7y cos

Last updated: 10/28/2023

Verify the identity cos 7x 7y cos 7x 7y 2 cos 7x cos 7y cos 7x 7y cos 7x 7y cos 7x cos 7y 63 13 sin 7x sin 7y