практ

uses graphAbc;
var x1,y1,k,g,per:integer;
x0,y0,x,y:real;
Begin
setwindowsize(800,600);
line(0,300,800,300);
line(400,0,400,600);
setpencolor(clred);
while g<>800 do
 begin
 g:=g+20;
 if g=400 then continue;
 line(g,290,g,310);
 end;
g:=0;
while g<>600 do
 begin
 g:=g+20;
 if g=300 then continue;
 line(390,g,410,g);
 end;
setpencolor(clgreen);
k:=20;
x0:=400;
y0:=300;
x:=-12;
y:=0.5*x*cos(2*x);
x1:=trunc(x0+(x*k));
y1:=trunc(y0-(y*k));
moveto(x1,y1);
while x<12 do
 begin
 x:=x+0.01;
 y:=0.5*x*cos(2*x);
 x1:=trunc(x0+(x*k));
 y1:=trunc(y0-(y*k));
 lineto(x1,y1);
 end;
setpencolor(clbrown);
k:=20;
x0:=400;
y0:=300;
x:=-15;
y:=sin(x)/cos(x);
x1:=trunc(x0+(x*k));
y1:=trunc(y0-(y*k));
moveto(x1,y1);
while x<15 do
 begin
 x:=x+0.001;
 y:=sin(x)/cos(x);
 x1:=trunc(x0+(x*k));
 y1:=trunc(y0-(y*k));
 if per-y1>0 then lineto(x1,y1)  else  moveto(x1,y1);
 per:=y1;
 end;