Question

How do you find the general solutions for `2cos^(2)x + 3cosx -2 = 0`?

Answer 1

`60` degrees
or
`pi/3` radians

Explanation:

Treat `cosx` as just `x`, so now we get `2x^2+3x-2=0`
Factor: `(2x-1)(x+2)=0`
Now replace `x` with `cosx`:
`(2cosx-1)(cosx+2)=0`
Now find out `x`
1:
`2cosx-1=0`
`2cosx = 1`
`cosx=1/2`
`x=60`

2:
`cosx=-2`
`x=und`