Question

How do you find all solutions of the following equation in the interval [0,2pi] of `2cos^2x-cosx=0`?

Answer 1

`pi`/3, `pi`/2, 3`pi`/2 and 5`pi`/3.

Explanation:

Factorize
Factor cos x = 0 gives solutions x = `pi`/2 and 3`pi`/2.
Factor 2 cos x `-`1 = 0 give the other two solutions
Use cos ( 2`pi` `-` x ) = cos x..