If sin(x) = 3/5 and x is in the second quadrant, what is cos(x)?
Correct: B
Since sin^2(x) + cos^2(x) = 1, cos^2(x) = 1 - sin^2(x) = 1 - (3/5)^2 = 1 - 9/25 = 16/25. So cos(x) = ±4/5. Since x is in the second quadrant, cos(x) is negative. Therefore, cos(x) = -4/5.