Ah hold on I think I misunderstood something, I can't seem to get 4 answers where theta is between -180 and 180 degrees.
To solve tan(x) = 1 (x between -360 deg and 360 deg), we get the solution of x = 45 deg. in the first quadrant.
So the solutions will be: x = 45 deg, 225 deg, -135 deg, -315 deg. (Basically add multiples 180 deg. from the 45 deg. solution (multiples include negative multiples), because the period of the tan(x) function is 180 deg.)
So the solutions for theta are obtained by just halving these solutions.