Cofunction Identities are explain how complentary angls and trig functions relate to one another.
| Cofunctiion Identities in Degrees | Cofunction Identities in Radians |
| sin (90° - θ) = cos θ | sin (π/2 - θ) = cos θ |
| cos (90° - θ) = sin θ | cos (π/2 - θ) = sin θ |
| tan (90° - θ) = cot θ | tan (π/2 - θ) = cot θ |
| cot (90° - θ) = tan θ | cot (π/2 - θ) = tan θ |
| sec (90° - θ) = cosec θ | sec (π/2 - θ) = cosec θ |
| csc (90° - θ) = sec θ | csc (π/2 - θ) = sec θ |