# How do you solve #3cos^2 x - 5cos x -1= 3 sin^2 x#?

##### 1 Answer

The description looks long, but I've written every single step so that anyone can understand!

#### Explanation:

from here its just a quadratic equation. you divide it to its factors.

from here u get two possibilities

the first answer cannot be true because the cosines should be between -1 and +1

if u remember the cosine curve u should be able to understand what im talking about.

so we are left with the latter answer

according to the trig equations

just replace the correct places of this equations with our answer

so the answer is