Prove theorem 4.2.18: The median to the hypotenuse of a right triangle is one-
half the length of the hypotenuse.
Clearlly not the only way:
1--Consider right triangle ABC wih C the right angle
2--Draw BC' equal and parallel to AC and AC' wqual to and parallel to BC.
3--The figure thus created is rectangle ABCC' with the diagonals (the two hypotenuses of triangles ABC and AC'B) crossing at D
4--Since the diagonals of a rectangle bisect one another, CD, a median of triangle ABC is equal to AB/2.
4--Similar statement s can be made about AD, BD and DC'.