Question

Please Help! Angle θ forms a reference angle that is below the positive x-axis (in quadrant IV). What will be the signs on the sine and cosine of angle θ?

Answer 1

sin(θ) is negative, cos(θ) is positive

Explanation:

Cosine corresponds to the x-coordinate within the unit circle, sine corresponds to the y-coordinate. In quadrant I, they are both positive, in quadrant II, x is negative whilst y is positive, and you would just continue by how they correspond as show in the unit circle, therefore, in quadrant IV, x is positive, y is negative.