Question

1+cos(12x)=

Answer 1

hint :
1 + cos(a) = 2 cos^2 (a/2)

Answer 2

on both side just change here a = 12x
what do you get ?

Answer 3

i don't understand the problem

Answer 4

i think the question asking us to simplifying of 1+cos(12x)
just use the identity like shown above :
1 + cos(a) = 2 cos^2 (a/2)

put a = 12x on both side, get

1 + cos(12x) = 2 cos^2 (12x/2) = 2cos^2 (6x)