Fundamental Trigonometric Identities

Pythagorean Identity 1

cos²x + sin²x = 1

Pythagorean Identity 2

1 + tan²x = sec²x

Pythagorean Indentity 3

cot²x + 1 = csc²x

Cofunction Identity - Sine

sin (pi/2 - x) = cosx

Cofunction Identity - Cosine

cos (pi/2 - x) = sinx

Cofunction Identity - Tangent

tan(pi/2 - x) = cotx

Cofunction Identity - Cotangent

cot(pi/2 - x) = tanx

Cofunction Identity - Secant

sec(pi/2 - x)= cscx

Cofunction Identity - Cosecant

csc(pi/2 - x) = secx

Odd-Even Identity →sin(-x) =?

-sinx

Odd-Even Identity →cos(-x) = ?

cosx

Odd-Even Identity →tan(-x)

-tanx

Odd-Even Identity →csc(-x) = ?

-cscx

Odd-Even Identity →sec(-x) =?

secx

Odd-Even Identity →cot(-x) = ?

-cotx