# Math Help - Radicals in trigonometric ratios

1. ## Radicals in trigonometric ratios

I was wondering how would i find x degree if 3√ 5 is the hypotenuse and 3 is the adjacent side I would have to use cos-1. The 3√ 5 is what i don't understand the most how would i put that into a TI calculator? Thanks for your help.

2. Hello,

There's a square root sign in a TI. In my TI89, it's above the multiplication sign ( $\boxed{\text{2nd}} ~ \times$)

Is it what you were looking for ?

3. Not really, I was looking for how to find out how to solve x degrees with using cosine. my calculator won't let me put cos-1(3/3√ 5).

4. Originally Posted by Jubbly
Not really, I was looking for how to find out how to solve x degrees with using cosine. my calculator won't let me put cos-1(3/3√ 5).
you have to put the entire denominator in parentheses ...

$\cos^{-1}(3/(3\sqrt(5)))$

or, you can try simplifying first ...

$\frac{3}{3\sqrt{5}} = \frac{1}{\sqrt{5}}$

now try it

5. And press the green diamond + enter to get an approximate value. (I only know what command to do with a TI89, not with a 80,82,83 or 84)