Question

__cos b = 1/2 [cos (a+b) + cos (a-b)] A. sin(a) B. sin(b) C. cos(a) D. cos(b)

Answer 1

Answer:

C is correct

COS (A) is right

Step-by-step explanation:

Answer 2

Answer:

cos(a)

Step-by-step explanation:

I substituted it on a calculator:

a = 30

b = 45

1/2 [ cos (a + b) + cos (a - b)]

1/2 [ cos (30 + 45) + cos (30 - 45)] = Sqrt6/4

cos(a)cos(b)

cos(30)cos(45) = Sqrt6/4