procedure trapez(a,b,h:real; var p:real);
var s:real;
begin
s:=a+b;
p:=1/2*s*h
end;

function trapez(a,b,h:real):real;
var s:real;
begin
s:=a+b
trapez:=1/2*s*h;
end;


program dzialka;
uses crt;
var a,b,h,p:real;
procedure trapez(a,b,h:real; var p:real);
var s:real;
begin
s:=a+b;
p:=1/2*s*h
end;
begin
clrscr;
writeln('podaj a i b ę);
readln(a,b);
writeln('podaj wysokosc trapezu ');
readln(h);
trapez(a,b,h,p);
writeln('trapez=', p:0:4);
readln;
end.