Prove that each of the following equations is an identity. In other words, prove that they are each true for all values for which the functions are defined. Homework Help ✎
sin2θ + cos2θ = 1
Recall the trigonometric ratios for sinθ, cosθ, and tanθ.
Substitute trigonometric ratios for tanθ and sec2θ.
(sinθ)(sin2θ + cos2θ)