find all solutions of the equation 4cos^2x-4cosx+1=0

Answer 1

Let cos x = y and solve the resulting equation

4y^2 -4y +1 = 0

That equation can be rewritten

(2y-1)^2 = 0

The only solution is

y = cos x = 1/2

x = cos^-1 1/2

Which angles x have cos x = 1/2 ?

There are two solutions between x = 0 and x = 2 pi