MathsIsFun - Trigonometric Identities
Unknown
Illustrated school-level page deriving the basic trigonometric identities from a right triangle: reciprocal and quotient relations, the Pythagorean identities, and angle sum, double-angle and half-angle formulas. Readers can recall the core identities and use them to rewrite simple trigonometric expressions.
More resources on Trigonometric Identities
Art of Problem Solving - Trig Identities Wiki
Wiki reference page from Art of Problem Solving listing Pythagorean, angle addition, double-angle, half-angle, product-to-sum and sum-to-product identities, with derivations for several. Readers can look up and justify the identities needed to simplify expressions in competition problems.
Trigonometry Khan Academy
Master law of sines & cosines with Sal Khan's free Trigonometry course! Ace triangles & trigonometry calculations.
mathsisfun.com
MathIsFun.com is a beginner-friendly math site that explains concepts with clear, step-by-step lessons and interactive activities. It covers topics from algebra and linear equations to geometry, fractions, data, and more, with practice problems, worksheets, and quizzes.