9.5 Trigonometric equations

Ideas in this lesson

Solve sine equations

Find a reference angle and include both matching quadrants within the stated interval.

Solve cosine equations

Use the even symmetry of cosine and its period to find every solution in the interval.

Solve tangent equations

Tangent repeats after a half-turn. Exclude inputs where tangent is not defined.

Multiple-angle equations

Solve over the full multiplied interval, then divide every candidate by the input coefficient.