Question

Find all solutions to the equation. cos^2x + 2 cos x + 1 = 0

Answer 1

clueless?? Help!!!

Answer 2

let z = cos(x), so the equation turns into z^2 + 2z + 1 = 0

if you solve z^2 + 2z + 1 = 0, what solutions do you get?

Answer 3

well it looks like the basic form to the quadratic formula, do i need to use the quadratic formula?

Answer 4

@jim_thompson5910

Answer 5

yes that is a good method to use

Answer 6

you can also factor, but factoring doesn't always work which is why the quadratic formula is a better method.

Answer 7

Here is one

Answer 8

thank you @Allenismyname and @jim_thompson5910 i figured it out the trig fuctions confused me