O Level
O-Level Additional Mathematics: Trigonometric Identities & Equations
•By Intuitional Team•1 min read
O-Level Additional Mathematics — Trigonometric Identities & Equations: quick notes, common traps, and an exam-style example.
Trigonometric identities
Core: sin²θ + cos²θ = 1, 1 + tan²θ = sec²θ. Use double-angle (sin2θ, cos2θ) and compound-angle (sin(A±B)) identities to simplify.
Proof tips
Always start from one side, use expansions, and convert everything to sin/cos if stuck.
Exam habits
- Memorise exact values (30°, 45°, 60°).
- Watch out for domain restrictions when solving trig equations.
- Show all steps in proving identities.
Tags
O-LevelAdditional MathematicsTrigonometric Identities & Equations