Answer:
angle bisector
Explanation:
In the picture shown in the question, the line segment SQ would be considered the angle bisector. This is because it is dividing the interior angles' opposite side into two line segments. Hence the line segments PQ and QR. The angle bisector divides the opposite side into line segments that are proportional to the other two sides of the triangle which in this case can be seen by the top left indication in the picture stating that PQ and QR are the same.