Question

Sharon made a scale drawing of a triangular park. The coordinates for the vertices of
the park are:
(– 10, 5)
(15, 5)
(10, 12)
Her scale is 1 unit = 1 meter.
What is the area of the triangular park in square meters?

Answer 1

Calculate the determinant (3 x 3 matrix). Then divide it by two and get the absolute value. That's the area.
Let the z-coordinate be equal to 1:

-10 | 5 | 1
15 | 5 | 1
10 | 12 | 1

The determinant of this set up is 175.
Area is therefore, | 175/2 | = 87.5 units

Hope this helps~ `u`