Which is the correct cofunction identity for cos thetaA. csc(90° - theta)B. sec(90° - theta)C. sin(90° - theta)D. cos(90° - theta)E. tan(90° - theta)
Accepted Solution
A:
Answer:C. sin(90° - θ)
Step-by-step explanation:A trig function of an angle equals the cofunction of the angle's complement.
The cofunction of cosine is sine, and the complement of θ is 90° - θ.
∴ cosθ = sin(90° - θ)