Written by the Fiveable Content Team • Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 exam•Written by the Fiveable Content Team • Last updated September 2025
Definition
Trig identities are mathematical equations involving trigonometric functions that are true for all values of their variables. They help simplify complex trigonometric expressions and solve equations.
Related terms
Pythagorean Identity: The Pythagorean identity relates sine and cosine functions with squares of each other. It states that sin^2(x) + cos^2(x) = 1.
Double Angle Identity: The double angle identity allows you to express trigonometric functions of double angles in terms of single angles. For example, sin(2x) = 2sin(x)cos(x).
Reciprocal Identity: The reciprocal identity shows the relationship between trigonometric functions and their reciprocals (cosecant, secant, cotangent). For example, csc(x) = 1/sin(x).