I did get the right answers, but I still would like to make sure my thinking is accurate, and also check if I made unnecessary calculations somewhere.
Get all the solutions to the trigonometric equation
in the interval [0, 2pi[
What I did was:
We set u = cos^2 and get
which gives us u = 0 and u = 1.
cos^2 x = 0 gives us cos x = +/- 0. x = pi/2 + k(pi).
cos^2 x = 1 gives us cos x = +/- 1. x = 0 + k(pi).
So the solutions are, in order,
0, pi/2, pi, 3pi/2.
I apologize for the mix and match between Latex and regular text.