Double Angle Identities (Grade 12 NSC Matric Mathematics): Quizzes

Trig values of $2α$ using values of $α$

$2 \sin α \cos α$

$\cos^2 α - \sin^2 α$

$1 - 2 \sin^2 α$

From compound angle formulae with $α = β$

$0.866$

Three

$1 - 2 \sin^2 α$

$θ = 90° + k × 180°$, $k ∈ ℤ$

Pythagoras theorem