11. Imagine that the stone is part of an arch, and that there is an isosceles triangle JEF formed by extending sides GE and HF downward. Use the measure of the angles of the trapezoid to find to measure of the base angles JEF and JFE. Add these measurements to your drawing.(2 points, one for each angle measure) 12. Find the measure of the vertex angle EJF. (1 point) 13. The isosceles triangle EJF is one of an unknown number of isosceles triangles from the original arch. Each isosceles triangle had the same vertex angle as triangle EJF. The sum of the vertex angles equals 180°. (2 points, one for the correct equation, one for the correct solution.) Let x = the number of isosceles triangles. Fill in the equation with your answer from Q12 and solve for x. ___ • x = 180 14. There is one stone for each isosceles triangle. How many stones were in the original arch? (1 point)