Simple Trig help

[UnD]

Lol this one troubling me badly.

Simplify 1+cos(180+2u) let 90+u be f
1+cos(2f)
then 1+ cos^2 (f) - sin^2 (f)
umm then it's 2 Cos^2 (f)

lol i'm a bit lost.

what do you after that lol, or do you do it an easier way .Thanks in advance :cry:

[Tzar]

Easier way. Dont forget that cos(180+X) = -cos(X)
Therefrore cos(180+2u) = -cos(2u). Can u go from there?

[UnD]

Ah yea. lol thanks very much. I can.