Review the proof of cos(A - B) = cosAcosB + sinAsinB.
Which of the following complete step 4 of the proof?
1 and 1
2 and 1
(cosAcosB)2(sinAsinB)2 and (cos2(A – B))((sin2(A – B))
(cos2A + sin2A)(cos2B + sin2B) and (cos2(A – B))(sin2(A – B))

