1. find the exact value of cos2θ if sin 2θ=3/4 and θ is between 0° and 90° 2. verify that sinθ(cos²θ-cos2θ)=sin³θ

Identities used:

sin²θ + cos²θ = 1cos2θ = cos²θ - sin²θ

#1

sin2θ = 3/4, and θ in the first quadrantcos²2θ = 1 - sin²2θcos2θ = √(1 - sin²2θ) = √(1 - 9/16) = √(7/16) = √7 / 4

#2

sinθ(cos²θ - cos2θ) = sinθ(cos²θ - (cos²θ - sin²θ) = sinθ(sin²θ) = sin³θ

Answer\ __o_o__/ lil i don’t kniw

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