Find the area of the figure. Round to the nearest tenth if necessary.
L(3,6), M(7,3), N(6,-1), J(2,-1), K(3,3)
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Use this method:
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L M N J K L
3 7 6 2 3 3
6 3 -1 -1 2 6
Add the diagonal products starting at the upper left.
3*3 + 7*-1 + 6*-1 + 2*2 + 3*6 = 9-7-6+4+18 = 18
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Add the diagonal products starting at the lower left.
6*7 + 3*6 + -1*2 + -1*3 + 2*3 = 42+9-2-3+6 = 52
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The difference = 52-18 = 34
The area is 1/2 that
Area = 17 sq units.
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This works for any polygon.
The points have to be in order around the polygon is the only restriction.