Math help ! Medals will be given !

Question

anonymous · Answer

attachment

anonymous · Answer

@phi @Luis_Rivera

anonymous · Answer

@amistre64

anonymous · Answer

@cwrw238

anonymous · Answer

oh if u ever come across a problem that a picture, go to www.google.com and click images.. then you can upload an image and search through that (unless u didn't know this already!) it helps me all the time

anonymous · Answer

The value inside of the parentheses happens to be the cosine of a very special angle.

anonymous · Answer

Okay, so what do i do next ?

anonymous · Answer

@Numb3r1

anonymous · Answer

Can someone please help me ?

anonymous · Answer

So if you know the angle that has that value as the cosine, that is the value of this function. Arccosine basically just asks "what angle has me as the cosine?"

anonymous · Answer

Alright. So what do i have to do to get my answer ?

anonymous · Answer

@experimentX

anonymous · Answer

Think, there's a special triangle with sides $$1/2:\sqrt3/2:1$$What angles does it have again?

anonymous · Answer

@Luis_Rivera .. its not like you were any help at all either!!! I was just giving a tip...!!

anonymous · Answer

What do you mean what angles ?

anonymous · Answer

The triangle with that ratio in its sides also has very neat angles. What are they?

anonymous · Answer

For this, @GabiMB 's tip actually could help.

anonymous · Answer

Ughhhhh ! How can you put the picture on google?

anonymous · Answer

thanks you @Numb3r1 
and here's how you do it on google: 
|dw:1368650513890:dw|