Реферат: Вычисления площади произвольного многоугольника

Assign(f,'points.dat');

reset(f);

readln(f, n);

for i:=1 to n do readln(f, sd[i].x, sd[i].y);

end;

function St(x1,y1, x2,y2, x3,y3: real): real;

var a, b, c, p: real;

begin

a:=sqrt(sqr(x1-x2)+sqr(y1-y2));

b:=sqrt(sqr(x1-x3)+sqr(y1-y3));

c:=sqrt(sqr(x3-x2)+sqr(y3-y2));

p:=(a+b+c)/2;

St:=sqrt(p*(p-a)*(p-b)*(p-c));

end;

function cross(c: integer): boolean;

var a, b, i: integer;

AA, BB, CC,

AA1, BB1, CC1: real;

function Mline(x,y: real): real;

begin

Mline:=AA*x+BB*y+CC

end;

function Sline(x,y: real): real;

begin

Sline:=AA1*x+BB1*y+CC1

end;

begin

if c=1 then

begin