Program BTH;
Uses crt;
var dl,dn,s,cao:real;
Begin
clrscr;
Write('Nhap canh day lon: ');readln(dl);
Write('Nhap canh day nho: ');readln(dn);
Write('Nhap chieu cao: ');readln(cao);
s:=(dl+dn)*cao/2;
Writeln('Dien tich hinh thang la: ',s:4:2);
readln;
end.