Cofunction identities - Trigonometric Identities

Cofunction identities

Lessons

Notes:
Cofunction Identities: Basically, we need the sum of the left and right brackets to be 90° or π2\frac{\pi}{2}

sin(π2θ)=cos(θ)\sin(\frac{\pi}{2}-\theta)=\cos(\theta)
sin(θ)=cos(π2θ)\sin(\theta)=\cos(\frac{\pi}{2}-\theta)
tan(π2θ)=cot(θ)\tan(\frac{\pi}{2}-\theta)=\cot(\theta)
tan(θ)=cot(π2θ)\tan(\theta)=\cot(\frac{\pi}{2}-\theta)
sec(π2θ)=csc(θ)\sec(\frac{\pi}{2}-\theta)=\csc(\theta)
sec(θ)=csc(π2θ)\sec(\theta)=\csc(\frac{\pi}{2}-\theta)
  • 3.
    Solve for xx
Teacher pug

Cofunction identities

Don't just watch, practice makes perfect.

We have over 250 practice questions in Trigonometry for you to master.