Question

If sin x = 0.20, cos x = .98, sin y = .12, and cos y = .99, which of the following is cos(x + y)

Answer 1

use the identity :
cos(x + y) = cos(x)cos(y) - sin(x)sin(y)

Answer 2

therefore,
cos(x + y) = 0.98(0.99) - 0.20(0.12) = ....
simplify that

Answer 3

i didnt get an available answer @RadEn

Answer 4

A. .07
B. .78
C. .70
D. .80

Answer 5

maybe something typo one of the values given above ??