Reciprocal, Quotient, & Pythagorean Identities

cos²ϴ + sin²ϴ

1

sin²ϴ + cos²ϴ

1

secϴ (reciprocal)

1/cosϴ

tanϴ (reciprocal)

1/cotϴ

sinϴ (reciprocal)

1/cscϴ

cosϴ (reciprocal)

1/secϴ

csc (reciprocal)

1/sinϴ

cotϴ (reciprocal)

1/tanϴ

Even functions

cos(-ϴ) = cos(ϴ) & sec(-ϴ) = sec(ϴ)

cotϴ (quotient)

cosϴ/sinϴ

cot²ϴ + 1

csc²ϴ

Sine, cosecant, cosine, & secant

have period of just 2π (360)°

Tangent & cotangent

have period of π (180°) & 2π (360)°

x²+y²

r²

1 + tan²ϴ

sec²ϴ

Odd functions

sin(-ϴ) = -sin(ϴ), csc(-ϴ) = -csc(ϴ), tan(-ϴ) = -tan(ϴ), cot(-ϴ) = -cot(ϴ)

tanϴ (quotient)

sinϴ/cosϴ