(a) Two of the three triangles specified in Exercise 13 are right triangles. Find th...

(a) Two of the three triangles specified in Exercise 13 are right triangles. Find their areas.

(b) Calculate the area of the remaining triangle in Exercise 13 by using the following formula for the area A of a triangle with vertices

The derivation of this formula is given in Exercise 34.

(c) Use the formula given in part (b) to check your answers in part (a).

Reference

In each case, determine whether the triangle with the given vertices is a right triangle.