If tan θ = 1/2 (acute), find sin 2θ:
A1/5
B3/5
C4/5
D2/5
Answer & Solution
Correct answer: C. 4/5
sin 2θ = 2 sinθ cosθ. From tan = 1/2, draw right triangle: opp=1, adj=2, hyp=√5. sinθ = 1/√5, cosθ = 2/√5. So sin 2θ = 2(1/√5)(2/√5) = 4/5.
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