Thanks. graphing the quad helped calculate the area as a sum of two triangles.

ht = sqrt((0-1.5)^2 + (1-2.5)^2) = 1.5sqrt(2)

base = sqrt((1-4)^2 + (3-0)^2) = 3sqrt(2)

Area of 1 triangle = 1/2 *1.5sqrt(2)*3*sqrt(2) = 4.5

Area of quadrialater = 2*area of triangle = 9