Simplify the expression:
tan [2arccos(x/4)]

Question

Simplify the expression:
tan [2arccos(x/4)]

anonymous · Answer

Convert arc cos to arctan..

poofypenguin · Answer

how would i go about doing that? 
I've never actually seen inverse trig functions before... i'm not really sure how they work..

anonymous · Answer

Let ;
$$\cos^{-1}(\frac{x}{4}) = y \implies \cos(y) = \frac{x}{4}$$

Find tan(y) first..

anonymous · Answer

Then you should learn what are inverse trigonometric functions and you should remember the formulas related to Inverse trigonometric functions..

poofypenguin · Answer

Would you recommend any resources? My textbooks have nothing on this...and i haven't seen them in high school before...

poofypenguin · Answer

I do understand what you did in your previous post, but how would you find tan(y)?

klimenkov · Answer

http://en.wikipedia.org/wiki/Inverse_trigonometric_function

anonymous · Answer

tan [2arccos(x/4)]
Let's see, let y=arccos(x/4) so this means cosy = x/4... 
So,
tan [2arccos(x/4)] = tan [2y] = $\Large \frac{2tany}{1-tan^2y} $...
Now, look at the triangle in the drawing:  |dw:1348300313074:dw|