Strategy for Trigonometric Equations (AQA A-Level Mathematics): Quizzes

$2\sin^2 \theta - \sin \theta - 1 = 0$

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

$\theta = \theta_0 + 360^\circ n$

$\theta = \theta_0 + 180^\circ n$

$0^\circ$ to $360^\circ$

To discard extraneous solutions

$(2u - 1)(u - 1) = 0$

$30^\circ, 150^\circ$

$0 \leq 3\theta \leq 540$

An angle more complicated than just $\theta$