posted by Shay .
The vertices of a triangle are A(13,13), B(9,3), and C(-1,1).
Determine the equation of the median AM, where M is the midpoint of BC.
Midpoint M of BC = ((9-1)/2,(3+1)/2)
slope AM = (13-2)/(13-4) = 11/9
So the equation of the median is
11x - 9y + c = 0, (knowing that the slope of Ax + By + C = 0 is -A/B)
substitute one of the points, say (4,2)
11(4) - 9(2) + C = 0
the equation of the median is 11x - 9y - 26 = 0
I use this method of finding the equation of a straight line if the slope is a fraction.
It gives the equation very quickly in the general form without any fractions.