Question 602278
To simplify the notation, let x=theta
cos(x/2) = sec(x/2) = 1/cos(x/2)
This gives cos^2(x/2) = 1
Using the identity cos^2(x/2) = 1/2(1+cos(x)), we can write
1/2(1+cos(x)) = 1
This gives
cos(x) = 1
On the interval 0 <= x <= 2{{{pi}}}, the solutions are 0 and 2{{{pi}}}