(a) Show that the area of the triangle with vertices P1(x1, y1), P2(x2, y2), and P3(x3,...

(a) Show that the area of the triangle with vertices P₁(x₁, y₁), P₂(x₂, y₂), and P₃(x₃, y₃) is given by the absolute value of the expression

(b) Use part (a) to find the area of the triangle with vertices (1, 2), (2, 3), and (−4,−4).