OK, I have a picture which will hopefully make my explanation a bit clearer.
I have a line $(a, b)$ to $(x, y)$ and all I know is the end points of the line.
I am trying to draw a line from the end point of the original line.
It will have an angle of $\theta$ from the original line and a length of $l$.
Based on these two values I need to work out the coordinates of the end point of this new line.
Length l can be any positive value. Angle theta can lie anywhere from $-80^\circ$ to $+80^\circ$.
Thanks for any help you can provide!
::Gets out pen and paper and starts scribbling::