Trig Identities

Reciprocal
sinθ =

1/cscθ

Reciprocal
cosθ =

1/secθ

Reciprocal
tanθ =

1/cotθ

Quotient
tanθ =

sinθ/cosθ

Quotient
cotθ =

cosθ/sinθ

Pythagorean
sin²θ + ____ = 1

cos²θ

Pythagorean
1 + ____ = sec²θ

tan²θ

Even-Odd
sin(-θ) =

-sinθ

Even-Odd
cos(-θ) =

cosθ

Even-Odd
tan(-θ) =

-tanθ

Even-Odd
csc(-θ) =

-cscθ

Even-Odd
sec(-θ) =

secθ

Even-Odd
cot(-θ) =

cotθ

Confunction
sin(90°- θ) =

cosθ

Confunction
cos(90°- θ) =

sinθ

Confunction
tan(90°- θ) =

cotθ

Confunction
csc(90°- θ) =

secθ

Confunction
sec(90°- θ) =

cscθ

Confunction
cot(90°- θ) =

tanθ

90° also equals

π/2 (pi over 2)