(Drag points) Draw a circle with three random points on the circle. Connect the points to form a triangle. Display the angles in the triangle

(Drag points) Draw a circle with three random points on the circle. Connect the points to form a triangle. Display the angles in the triangle. Use the mouse to drag a point along the perimeter of the circle. As you drag it, the triangle and angles are redisplayed dynamically, as shown in Figure 15.30b. For computing angles in a triangle, see Listing 4.1.

 (b) Exercise 15.21 enables the user to drag vertices along the circle and display the angles in the triangle dynamically.