Complete Trigonometric Identities Cheat Sheet
By Dr. Iris Vaughan, Mathematics Editor·Published 15 October 2025·Last reviewed 20 January 2026
All six categories of trig identities — Pythagorean, angle addition, double angle, half angle, product-to-sum, sum-to-product — on a single printable reference.
Key Formulas
Pythagorean: sin²θ+cos²θ=1
Addition: sin(A+B)=sinAcosB+cosAsinB
Double: sin(2θ)=2sinθcosθ
Half: sin²θ=(1−cos2θ)/2
Product-sum: sinAcosB=½[sin(A+B)+sin(A−B)]
Download Printable PDF
Get this cheat sheet formatted for A4 or US Letter printing — no ads, clean layout, exam-ready. $9 via Gumroad.
View in Shop