Let A(x1, y1) = (3, 4), B(x2, y2) ≡ (0, 5), C(x3, y3) ≡ (2, –1)and D(x4, y4) ≡ (3, –2) be the vertices of quadrilateral ABCD.Area of quad. ABCD = \(rac{1}{2}\) |{(x1 y2 – x2 y1) + (x2y3 – x3y2) + (x3y4 – x4y3) + (x4y1 – x1y4)}|= \(rac{1}{2}\) |{(3 × 5 – 0 × 4) + (0 × (–1) – 2 × 5) + (2 × (–2) – 3 × (–1)) + (3 × 4 – 3 × (–2))}|= \(rac{1}{2}\) |{(15 – 0) + (0 – 10) + (– 4 + 3) + (12 + 6)}|= \(rac{1}{2}\) |{15 – 11 + 0 + 18}| = \(rac{1}{2}\)x 22 = 11 sq. units.