(a) Prove that the midpoint of the line segment from

(b) Find the lengths of the medians of the triangle with vertices A(1, 2, 3), B(-2, 0, 5), and C(4, 1, 5). (A median of a triangle is a line segment that joins a vertex to the midpoint of the opposite side.)

P:(x1, y1, Z1) to P(x2, y2, Z2) is X1 + x2 y + y2 Z1 + Z2 2 2