Strategy for Trigonometric Equations (Edexcel A-Level Mathematics): Flashcards

Understand which trig functions are involved.

Rearrange to get all trig functions on one side.

$\sin^2\theta + \cos^2\theta = 1$.

$\theta = \sin^{-1}(k) + 360°n$ or $\theta = 180° - \sin^{-1}(k) + 360°n$.

$u = \frac{-b \pm \sqrt{b^2-4ac}}{2a}$

$\theta = \theta_0 + 180°n$.

Verify by substituting back into the original equation.

Angles formed by the sum or difference of two angles.

Find $3\theta$, then divide by $3$.

Check for extraneous solutions.