Question

4cos(x+(pi/3))=

A) 2sqrt(3)cosx - 2sinx
B) 2cosx - 2sqrt(3)sinx
C) 2cosx + 2sqrt(3)sinx
D) 2sqrt(3)cosx + 2sinx
E) 4cos(x)+2

Answer 1

use the formula :
cos(A+B) = cos(a)cos(B) - sin(A)sin(B)
to get the value of cos(x+(pi/3))

Answer 2

then multiply by 4

Answer 3

so cos(x)cos(pi/3) = (1/2)cosx-(sqrt3/2)sinx

times 4 = B?

Answer 4

yes, the answer is B

Answer 5

ok thanks