Satisfying trig equations between (0,2pi)

[banfill_89]

Homework Statement

cos^2 x-cos x- 1= 0

Homework Equations

several trig identities involving cos

The Attempt at a Solution

i tried applying identites everywhere, no luck. I've tried using it as a trinomial...no luck...and I've tried adding one to both sides and still no luck...please help lol

 

[Mark44]

Homework Statement

cos^2 x-cos x- 1= 0

Homework Equations

several trig identities involving cos

The Attempt at a Solution

i tried applying identites everywhere, no luck. I've tried using it as a trinomial...no luck...and I've tried adding one to both sides and still no luck...please help lol

If you squint your eyes a bit, you might notice that this is a quadratic in cos x. Think about how you would solve x^2 - x - 1 = 0, but keep in mind that you're solving for the cosine of x, not x.