Trigonometry - Simple Identities (Edexcel A-Level Mathematics): Quizzes

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

$1 + \tan^2 \theta = \sec^2 \theta$

$\csc \theta = \frac{1}{\sin \theta}$

$\tan \theta = \frac{\sin \theta}{\cos \theta}$

$\cos \theta$

$-\sin \theta$

$\sin 2\theta = 2 \sin \theta \cos \theta$

Identical to; true for all values

It's not an identity; only true for specific $\theta$

Dividing loses the solution where $\sin \theta = 0$