Trigonometric Proof (Edexcel A-Level Mathematics): Flashcards

Understand the identity, simplify, and apply identities.

Examine the identity and decide which side to simplify.

Start with the side that looks more complex.

$\sin^2\theta + \cos^2\theta = 1$; $1 + \tan^2\theta = \sec^2\theta$; $\csc^2\theta = 1 + \cot^2\theta$.

Combine into one fraction and factor where applicable.

Convert all functions to sine and cosine for clarity.

Conclude with '$LHS = RHS$' to confirm identity is proven.

It equals $1$, derived from Pythagorean theorem.

It simplifies to $1$ using trigonometric identities.

$\sin(2\theta) = 2\sin(\theta)\cos(\theta)$.