First, find the distance between (-4, 0) and (-1, -3) by using the distance formula, you will get the √18 second, find the distance between (-4, 0) and (-3, 1), the result is √2 so the area is the √18*√2=6
Please refer to this website for the distance formula: http://www.mathwarehouse.com/algebra/distance_formula/index.php