Geo2.35

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Find the equation of the altitude from A to side BC of triangle ABC formed by A(1,1),B(-3,4),C(2,-5)\,

Given A(1,1),B(-3,4),C(2,-5)\,

The equation to the line BC is y-4={\frac  {-5-4}{2-(-3)}}(x+3)\,

5(y-4)=-9(x+3),5y+9x+7=0\,

The slope of the BC is {\frac  {-9}{5}}\,

The slope of the altitude to BC is {\frac  {5}{9}}\,

The line from A with the slope {\frac  {5}{9}}\, is

y-1={\frac  {5}{9}}(x-1)\,

9y-9=5x-5,5x-9y+4=0\,


Main Page:Geometry:Straight Lines-I