Aright triangle has one vertex on the graph of y =x,x>0, at (x, y), another at the origin, and the third on the positive y-axis at (0, y), as shown in the igure. Express the area A of the triangle as a function of x. y=x (0, y) (x, y) Ax) =D (Use integers or fractions for any numbers in the expression.) (0, 0)