Uses crt;
Var a, b, c, s, p: real;
Begin
Clrscr;
Write('Nhap a, b, c: '); readln(a, b , c);
s:=0; p:=0;
If (a+b>c) and (b+c>a) and (c+a>b) then 
Begin
    Writeln('Day la 3 canh cua tam giac');
    s:=1/2*a*h;
    p:=a+b+c;
    Writeln('Dien tich la: ',s:0:2);
    Writeln('Chu vi la: ',p:0:2);
End
Else writeln('Day khong phai la 3 canh cua tam giac');
Readln
End.

uses crt;

var a,b,c,s,cv:real;

begin

clrscr;

write('Nhap canh a: ');readln(a);

write('Nhap canh b: ');readln(b);

write('Nhap canh c: ');readln(c);

if (a+b>c) and (b+c>a) and(a+c>b) 

then begin

writeln('Day la ba canh tam giac');

cv:=a+b+c;

s:=(sqrt((a+b+c)*(a+b-c)*(b+c-a)*(a+c-b)))/4;

writeln('Chu vi: ',cv);

writeln('Dien tich: ',s);

end else writeln('Day khong phai ba canh tam giac');

readln

end.