Question

please solve it as soon as possible please in detail​

Answer 1

Answer:

1 = cosA cosB − sinA sinB cos(A − B) = cosA cosB + sinA sinB sin2 A + cos2 A = 1, sin 2A = 2 sinA cosA cos 2A = 2 cos2 A − 1=1 − 2 sin2 A 2 sinA cosB = sin(A + B) + sin(A − B) 2 cosA sinB = sin(A + B) − sin(A − B) 2 cosA cosB = cos(A + B) + cos(A − B)