Anytime you have a triangle (right triangles are preferred) where at least 2 angle measures and 1 side is known. Or, at least two sides and 1 angle measure.
OR..... 3 sides or three angles are known. So, sines or cosines could be used at almost anytime to find the sides and angles of a triangle!
It is the last one. A closed circle means less than or equal to, so that crosses out the top two. The third says five is greater and we know that is not true because the line is decreasing in value. It must be the fourth.
