Hello could someone please solve this question for me. I need to see the steps invloved as i am not really sure of what i am meant to be doing. Thankyou so somuch

Question

Using the identitysin^2theta + cos^2theta=1and the identities for cos(A+B) find:

cos 75degrees if cos 45degrees = .707, and cos 30degrees = 0.866

Trig