How to Solve Trigonometric Equations?
TL;DR: Solving a trig equation is a three-step rhythm. First, isolate the trig function on one side just like you’d isolate x in regular algebra. Next, find every reference-angle solution that lives in a single revolution (0 to 2 pi). Finally, tack on “plus 2 pi times any integer k” to capture every other rotation. […]