Question

Trigonometric functions of sum and
difference of angles

1-If cos (A + B) = a cos A cos B + ß sin A sini,
then (a, b) is
(A) (-1, -1)
(B) (-1,1)
(C) (1, -1)
(D) (1,1)
​

Answer 1

Answer:

c. (1, -1)

Step-by-step explanation:

cos(A+B) = 1. cos A cosB - {-1(sin A sin B)}

= cos A cosB + sin A sinB

hope it helps.. plz mark as brainliest...