\input{preamble-standalone.ltx} \begin{document} % Ex. No. 88 (Section 12.2.5 : Drawing a tangent option \tkzimp{from}) \begin{tikzpicture}[scale=.5] \tkzDefPoint(0,0){B} \tkzDefPoint(0,8){A} \tkzDefSquare(A,B) \tkzGetPoints{C}{D} \tkzDrawSquare(A,B) \tkzClipPolygon(A,B,C,D) \tkzDefPoint(4,8){F} \tkzDefPoint(4,0){E} \tkzDefPoint(4,4){Q} \tkzFillPolygon[color = green](A,B,C,D) \tkzDrawCircle[fill = orange](B,A) \tkzDrawCircle[fill = purple](E,B) \tkzDefTangent[from=B](F,A) \tkzInterLL(F,tkzFirstPointResult)(C,D) \tkzInterLL(A,tkzPointResult)(F,E) \tkzDrawCircle[fill = yellow](tkzPointResult,Q) \tkzDefPointBy[projection= onto B--A](tkzPointResult) \tkzDrawCircle[fill = blue!50!black](tkzPointResult,A) \end{tikzpicture} \end{document}