Michael J. answered 07/06/15
Tutor
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Effective High School STEM Tutor & CUNY Math Peer Leader
First, we need to know the double angle identity for sine.
sin2θ = 2sinθcosθ
sinθ is already given to us. We just need to find cosθ.
We know that sin2θ + cos2θ = 1
cosθ = √(1 - sin2θ)
Therefore,
sin2θ = 2sinθ√(1 - sin2θ)
Plug in the value of sinθ into the identity and simplify.