Trig Identities

Front

What happens when you multiply two reciprocal functions?

Back

It equals 1

Front

What is the Pythagorean identity?

Back

sin²(θ) + cos²(θ) = 1

Front

What is the definition of a reciprocal function?

Back

A function that is the inverse of another function, such that f(x) * f⁻¹(x) = 1.

Front

What is the quotient identity for tangent?

Back

tan(θ) = sin(θ) / cos(θ)

Front

What is the definition of sine in a right triangle?

Back

Sine is the ratio of the length of the opposite side to the length of the hypotenuse.

Front

What is the definition of cosine in a right triangle?

Back

Cosine is the ratio of the length of the adjacent side to the length of the hypotenuse.

Front

What is the definition of tangent in a right triangle?

Back

Tangent is the ratio of the length of the opposite side to the length of the adjacent side.

Front

What is the co-function identity for sine and cosine?

Back

sin(θ) = cos(90° - θ) and cos(θ) = sin(90° - θ)

Front

What is the double angle formula for sine?

Back

sin(2θ) = 2sin(θ)cos(θ)

Front

What is the double angle formula for cosine?

Back

cos(2θ) = cos²(θ) - sin²(θ) or cos(2θ) = 2cos²(θ) - 1