All the following questions required to find theta (or x or the angle) between 0 radians and 2pi radians.
First a linear example.
A linear example with a double angle. So we needed to solve for 2theta between 0 and 4pi to get theta between 0 and 2pi.
The next example required using the Pythagorean identity and a quadratic trigonometric equation.
Lastly one that required a double angle formula substitution and a surprising result.