Since you haven't provided the data to answer the problem, I have my notes here that might guide you solve the problem on your own:
Now, consider a triangle that’s graphed in the coordinate plane. You can always use the distance formula, find the lengths of the three sides, and then apply Heron’s formula. But there’s an even better choice, based on the determinant of a matrix.
Here’s a formula to use, based on the counterclockwise entry of the coordinates of the vertices of the triangle
(x1, y1), (x2, y2), (x3, y3) or (2, 1), (8, 9), (1, 8): A = x1y2 + x2y3 + x3y1 – x1y3 – x2y1 – x3y2.
