Two straight lines are perpendicular to each other, one of them touches the parabola =4a(x+a) and the other touches =4b(x+a) . Their point of intersection lies on the line
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
The second parabola is y^2=4b(x+b). Let y= m(x+a)+ a/m be the equation of the tangent to the first parabola and y = (-1/m)(x+b)-bm is the equation of the perpendicular tangent to the second parabola. On subtracting the equations,we get x+a+b=0.