Question

Just confused. Given tan(A) = 2 and A is in Quadrant I, find sin(2A).

A. 0
B. 1
C. 1/2
D. 4/5

Answer 1

draw your triangle

tanA = 2/1
sinA = 2/√5
cosA = 1/√5

sin2A = 2sinAcosA = 4/5