Question

HELP!
Find the exact value of cos(11π/12). Hint: begin by rewriting 11π/12 in terms of familiar angles.

Answer 1

\[\Huge \cos(\frac{11\pi}{12})=\cos(\pi-\frac{\pi}{12})\]

Answer 2

cos(x+y)= cos x cosy - sin x sin y use this identity

Answer 3

11π/12 = 8π/12 + 3π/12 = 2π/3 + π/4 i would use this

Answer 4

I really don't get how any of that helps me.

Answer 5

\(\bf \huge \frac{11\pi}{12} \implies \frac{8\pi}{12}+\frac{3\pi}{12}
\implies \frac{2\pi}{3}+\frac{\pi}{4}\)

Answer 6

http://s4.hubimg.com/u/5401027_f260.jpg

Answer 7

The answer choices are:
√6+√2/4
√3+2/4
√3-2?4
-√ 2-√6/4

Answer 8

so, add them then

Answer 9

Use the identity I have posted above. cos(x+y)= cos x cosy - sin x sin y

Answer 10

and your Unit Circle

Answer 11

Oh man, I got to go thanks for the help, I'll solve it when I get back, I still gave you the medal.