SOLUTION: Use the determinant to find the area of the triangle with the following vertices: (-3,1) (1,-3) (2,3) I know the area should be positive, but I'm still confused.

Question 624836: Use the determinant to find the area of the triangle with the following vertices:
(-3,1)
(1,-3)
(2,3)
I know the area should be positive, but I'm still confused.
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
Use the determinant to find the area of the triangle with the following vertices:
A (-3,1)
B (1,-3)
C (2,3)
-------
A_B_C_A
-3 +1 +2 -3
+1 -3 +3 +1
----------
Add the diagonals starting at the upper left
= 9 + 3 + 2 = 14
--------
Add the diagonals starting at the lower left
= 1 - 6 - 9 = -16
----------
The absolute value of the difference = 30
Area = 30/2 = 15 sq units
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