We are given the equation for line AD.
Line AC is perpendicular to BF.
A little math
= 8deg 7min 48sec
Which is half the angle CAB.
Thus we know the equation of line AB.
It is required that Line CH be perpendicular to AB.
The equation for Line CH: y =
Since H is not restricted to being on the line AB, the point C can occur anywhere on the line.