In triangle ABC with coordinate A(3,4), B(-5,2) and C(1,4) , line segment CF is the altitude of triangle ABC. Determine the equation of the line that collinear to line CF
the slope of AB is 1/4
So, you want a line with slope -4 that contains C(1,4).
Use the point-slope form, and you have
y-4 = -4(x-1)