Anybody can help me?

Which sum or difference identity would you use to verify that cos (180° - ∅) = -cos ∅? a. sin (α -β) = sin α cos β – cos α sin β b. cos (α -β) = cos α cos β – sin α sin β c. cos (α -β) = cos α cos β + sin α sin β d. sin (α + β) = sin α cos β + cos α sin β

Evaluate the expression for the given value of the variable 2×(c2-5) for c=4

Can someone check if i did this right since i really want to make sure it’s correct. if you do you so much