[pstricks] Ending a psline on pscircle
Herbert Voss
Herbert.Voss at FU-Berlin.DE
Wed Feb 12 19:22:33 CET 2014
Am 12.02.2014 18:30, schrieb Rich Shepard:
> When I draw a \psline from a point (whose coordinates I know from the
> grid
> and center of the \pscircle or \pselipse) to the boundary line of the
> \pscircle or \pselipse I end up tweaking the terminal coordinates until the
> line end (or terminal arrow point) just touches the boundary line. I'm
> certain there's a method to determining just what those terminal
> coordinates
Rich,
I suppose you are looking for something like that
\documentclass{minimal}
\usepackage{pstricks-add}
\begin{document}
\begin{pspicture}[showgrid](0,3)(10,10)
\psdot(2,4)\pscircle(7,7){2}
\psCircleTangents(2,4)(7,7){2}
\pcline[nodesep=-1cm,linecolor=blue](2,4)(CircleT1)
\pcline[nodesep=-1cm,linecolor=blue](2,4)(CircleT2)
\psdots(CircleT1)(CircleT2)
\uput[-80](CircleT1){T1}\uput[115](CircleT2){T2}
\end{pspicture}
\end{document}
There is also a \psEllipseTangents(x0 , y0)(a, b)(xp, yp)
Herbert
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