how to find two endpoints of a line..??

Hi...

I have a particular point on a curve.. This curve isnt a smooth curve.. anyways, i need to draw a tangent at this point.. i have the following information in hand:

1. Point P at which tangent has to be drawn.

2. Length l of the tangent.

Now i want the two end-points of the tangent in such a way that P is the mid-point of these new points.. I dont have equation of the curve. i dont know slope of the tangent..

Is there any way to do this.??

Thanks in advance

hmm..this might give u a clue

Does point P have coordinates? if they have you could solve for the equation of the slope of the tangent line by using the equation y-y'=m(x-x'). then all else will follow..you could reply to me..of course(Smirk)