>Knowing the initial data, how could I set up an equation >for y3, so that the length of the given section of the >parabola will be equal to the given length? I couldn't do >it on paper... Not quite sure I understand, do you want to know how much cord it will take to make a parabola-shaped cord go 5 feet from (x1, y1) to (x2, y2) and still touch (x3, y3)? >PG