can someone show me how to solve this?
Yes .. but there are two more (in $\displaystyle [0, 2\pi]$ anyway).
ex. $\displaystyle \tan x = 1$
$\displaystyle x = 45^{\circ}$ works ... but look in quadrant III as well
Also, since adding multiples of 2pi (360 degrees) will give you the same spot on the unit circle, then you could generalize your answer to $\displaystyle x = 45^{\circ} + n360^{\circ}$ where n is an integer. This applies to your 4 other answers.