Dropping a vertical line from point B perpendicular to the x-axis will form a square and a triangle:
From the figure, we see that the square has area s2 = 22 = 4 , and the triangle has area
Hence, the area of the quadrilateral is 4 + 1 = 5. The answer is (B). Note, with this particular solution, we
did not need to use the properties of the diagonal line in the original diagram.