Alg6.9

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Find the area of the triangle formed by (1,3),(3,-1),(-5,-5)\,

The formula for finding the area of the traingle formed by (x_{1},y_{1}),(x_{2},y_{2}),(x_{3},y_{3})\, is {\frac  {1}{2}}|[x_{1}(y_{2}-y_{3})+x_{2}(y_{3}-y_{1})+x_{3}(y_{1}-y_{2})]|\,

Aplying the formula,we get

{\frac  {1}{2}}|[1(-1+5)+3(-5-3)-5(3+1)]|\,

{\frac  {1}{2}}|4-24-20|\,

{\frac  {1}{2}}|-40|\,

Hence the area of the triangle is 20.


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