If cos theta=-3/5 in quadrant 2 what is sin theta?

a: 4/5
b: 3/4
c: -3/4
d: -4/5

Choice A) 4/5



Work Shown:

cos^2(theta) + sin^2(theta) = 1
(-3/5)^2 + sin^2(theta) = 1
9/25 + sin^2(theta) = 1
9/25 + sin^2(theta) - 9/25 = 1 - 9/25
sin^2(theta) = 1 - 9/25
sin^2(theta) = 25/25 - 9/25
sin^2(theta) = (25 - 9)/25
sin^2(theta) = 16/25
sqrt[sin^2(theta)] = sqrt[16/25]
sin(theta) = 4/5

The fact that sine is positive in quadrant 2 means that the result is positive.