Use δdef, shown below, to answer the question that follows

what is the value of x rounded to the nearest hundredth? type the numeric answer only in the box below

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

Can someone me out here number 4 plz

I'm confused on this could anyone me and show me what i need to do to solve it.