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

Question

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

dls · Answer

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

anonymous · Answer

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

anonymous · Answer

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

anonymous · Answer

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

jdoe0001 · Answer

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

jdoe0001 · Answer

anonymous · Answer

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

jdoe0001 · Answer

so, add them then

anonymous · Answer

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

jdoe0001 · Answer

and your Unit Circle

anonymous · Answer

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