# Math Help - Inverse function help

1. ## Inverse function help

Hi all.

Very stumped on this one, so a step by step guide would be amazing

cos theta = 0.53 where 0 _< theta _< 2pi

the "_<" means greater or equal to.

Thanks!

2. ## Re: Inverse function help

Hi FlexedCookie,

$\cos\theta=0.53\mbox{ where }0\leq\theta\leq2\pi$

The cosine function is positive in the first and fourth quadrants. Therefore,

$\theta=\pm\cos^{-1} 0.53$

You can find $\cos^{-1} 0.53$ using a trigonometric table or the calculator. Hope this clarifies your problem.