<PRE><B>Question 624836</B>
Use the determinant to find the area of the triangle with the following vertices:
A (-3,1)
B (1,-3)
C (2,3)
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A_B_C_A
-3 +1 +2 -3
+1 -3 +3 +1
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Add the diagonals starting at the upper left
= 9 + 3 + 2 = 14
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Add the diagonals starting at the lower left
= 1 - 6 - 9 = -16
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The absolute value of the difference = 30
Area = 30/2 = 15 sq units</PRE>