Standard form of parabola - Producing of Teaching Materials with Drawings Using KeTCindy

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Draw the standard form of the parabola and explain the focus and the directrix, etc.

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parabola.zip

• Put a geometric point A on the x-axis.

Putpoint("O",[0,0]);
Paramplot("1","[t^2/4/A.x,t]","t=[-3,3]");
／／ Draw the parabola with the parameter.

Putoncurve("P","gp1",[0,3]);
／／ Put a geometric point P on the parabola and we can move P in the range of x from 0 to 3.

Putpoint("H",[-A.x,P.y]);
Putpoint("B",[-A.x,0]);
／／ Put two geometric points H, B with the x-coordinate -A.x.

Putpoint("C",[-A.x,YMAX]);
／／ Put a geometric point C in order to write the name of the directrix.

Setcolor([0.7,0,0,0]);
／／ The following lines have the color cyan.

Lineplot("1",[B,B+[0,1]]);
Listplot("1",[A,P,H]);
Segmark("1",[A,P],["Type=1","Size=0.5"]);
Segmark("2",[P,H],["Type=1","Size=0.5"]);
／／ These marks represent that AP=PH.

／／ "Type=1" means only one line and "Size=0.5" means 0.5 times of the default length.

Paramark([B,H,P],[0.5]);
／／ Put the right angle mark at H. Remark the order of three points B, H, P.

Setpt(3);
／／ Set 3 times of the default size of the following points.

Drawpoint([A,P,H]);
／／ Put three points A, P, H.

Setcolor("black");
Expr([A,"s1","p",-A,"s1w","-p",C,"n","\ell"]);
Letter([P,"s1e","P$(x,\,y)$",A,"nw","F",H,"w1","H"]);