Angle θ is in standard position. If tanθ < 0 and cosθ = -4/5 , find sinθ.

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(1) Answers

EchoEdgeman

use the formula,
sin^2 x + cos^2 x =1
sin^2 x + (-4/5)^2 = 1
sin^2 x + 16/25 = 1
sin^2 x = 1-16/25
sin^2 x = (25-16)/25
sin^2 x = 9/25
sin x = +3/5 or -3/5
since both tan and cos are negative, sine will be positive (Quadrant 2).
sin x = 3/5.