If slope of a line is m then slope of the perpendicular line is -1/m .
so slope of perpendicular line is -3.
then use this y-y0=m(x-x0)
y+5=-3(x-2)
y+5=-3x+6
y=-3x+1
500 789 ........................................
If the drawing of your octagon (or whatever) has been separated into triangles, and one triangle's area<span> is labeled, then you do not need to know the apothem. Just take the </span>area<span> of that one triangle, and multiply by the number of sides in the original </span>polygon<span>.</span>
