Answer:
c. sin 30 is positive and sin -30 is negative
Step-by-step explanation:
Picture the unit circle (which is attached). Sine is like the y-coordinate. And -30 and 30 on the unit circle both form equally-sized triangles, but -30 is underneath the x-axis, so it has a negative y-coordinate. 30 is above the x-axis, so it has a positive y-coordinate.
