Равнобедренная трапеция задана координатами вершин

type koords=record x,y: real; end; var ab,dc,dh,ad,h: real; a,b,c,d: koords; begin writeln ('A: '); write ('X='); readln (a.x); write ('Y='); readln (a.y); writeln ('B: '); write ('X='); readln (b.x); write ('Y='); readln (b.y); writeln ('C: '); write ('X='); readln (c.x); write ('Y='); readln (c.y); writeln ('D: '); write ('X='); readln (d.x); write ('Y='); readln (d.y); ab: =sqrt (sqr (b.x-a.x)+sqr (b.y-a.y); dc: =sqrt (sqr (c.x-d.x)+sqr (c.y-d.y); dh: =abs (dc-ab) /2; ad: =sqrt (sqr (a.x-d.x)+sqr (a.y-d.y); h: =sqrt (sqr (ad) -sqr (dh); writeln ('H=',h: 0:4); readln; end.