На языке pascal:
1:
var
a,b,s:integer;
begin
writeln('Vvedite dliny storon:');
readln(a,b);
s:=a*b;
writeln('Ploshad pryamougolnika = ',s);
end.
2.
var
s,r:real;
begin
writeln('Vvedite R kruga:');
readln(r);
s:=pi*sqr(r);
writeln('Ploshad kruga = ', s);
end.