Trig Identities

Front

What is the Pythagorean identity for sine and cosine?

Back

sin²θ + cos²θ = 1

Front

What is the definition of tangent in terms of sine and cosine?

Back

tanθ = sinθ / cosθ

Front

What is the relationship between secant and cosine?

Back

secθ = 1 / cosθ

Front

What is the relationship between cosecant and sine?

Back

cscθ = 1 / sinθ

Front

What is the definition of cotangent in terms of sine and cosine?

Back

cotθ = cosθ / sinθ

Front

What is the double angle formula for sine?

Back

sin(2θ) = 2sinθcosθ

Front

What is the double angle formula for cosine?

Back

cos(2θ) = cos²θ - sin²θ

Front

What is the sum of angles formula for sine?

Back

sin(a + b) = sin(a)cos(b) + cos(a)sin(b)

Front

What is the sum of angles formula for cosine?

Back

cos(a + b) = cos(a)cos(b) - sin(a)sin(b)

Front

What is the product-to-sum formula for sine?

Back

sin(a)sin(b) = 1/2 [cos(a - b) - cos(a + b)]