11. the coordinates of endpoint a are a(5, -15). the midpoint of ac is b(5, -8). find the coordinate of endpoint c. (1 point work, 1 point x2, one point y2)
12. find the distance between a(12, 6) and b(-8, 18). leave your answer in simplest radical form. (1 point work, 1 point answer)
13. find the area of a circle with diameter 8 in. round to the nearest tenth. (1 point answer, 1 point units)