a = int(input())
b = int(input())
c = int(input())
if a**2+b**2==c**2:
    print(a,b,c,"la ba canh cua tam giac")
elif a**2+c**2==b**2:
    print(a,b,c,"la ba canh cua tam giac")
elif b**2+c**2==a**2:
    print(a,b,c,"la ba canh cua tam giac")
else:
    print(a,b,c,"khong la ba canh cua tam giac")

uses crt;
var a, b, c: real;
begin
clrscr;
 writeln('Kiem Tra Tam Giac');
    write('Nhap Ba Canh a, b, c:'); readln(a, b, c);
    if (a+b>c) and (a+c>b) and (b+c>a) then 
    begin
     writeln('Do La Ba Canh Tam Giac');
     if (a * a + b * b = c * c) or (a * a + c * c = b * b) or (b * b + c * c = a * a) then 
      writeln('Tam Giac Vuong')
     else if (a = b) or (a = c) or (b = c) then 
     begin
      if (a = b) and (b = c) then 
       writeln('Tam Giac Deu')
      else 
       writeln('Tam Giac Can');
     end
     else writeln('Tam Giac Thuong');
    end
    else write('Khong Phai Tam Giac');
    readln
end.

#include <bits/stdc++.h>
using namespace std;
int main() {
double a, b, c;
cin >> a >> b >> c;
if(a==b)
{if (b!=c) {cout << "Ba so da nhap la do dai ba canh cua mot tam giac can";}
if(b==c) {cout << "Ba so da nhap la do dai ba canh cua mot tam giac deu";}}
if(b==c)
{if(a!=b) {cout << "Ba so da nhap la do dai ba canh cua mot tam giac can";}}
if(a==c)
{if(a!=b) {cout << "Ba so da nhap la do dai ba canh cua mot tam giac can";}}
if(a!=b)
{if(b!=c) {cout << "Ba so da nhap khong la do dai ba canh cua mot tam giac can";}}
return 0;
}

Chúc bn học tốt! (Bonus thêm trường hợp không là độ dài tam giác cân và là độ dài của tam giác đều nha!)

Uses crt;

Var a, b, c:real;

Begin

Readln(a);

Readln(b);

Readln(c);

If (a + b > c) or (a + c > b) or (b + c > a) then writeln('tam giác')

Else writeln('Khong phai tam giac');

Readln

End.

uses crt;

var a,b,c:real;

begin

clrscr;

readln(a,b,c);

if (a>0) and (b>0) and (c>0) and (a+b>c) and (a+c>b) and (b+c>a) then 

begin

if (a=b) and (b=c) then write('Day la tam giac deu')

else writeln('Day khong la tam giac deu');

end

else writeln('Day khong la ba canh trong mot tam giac');

readln;

end.

uses crt;

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

begin

clrscr;

readln(a,b,c);

if (a>0) and (b>0) and (c>0) and (a+b>c) and (a+c>b) and (b+c>a) then 

begin

p:=(a+b+c)/2;

s:=sqrt(p*(p-a)*(p-b)*(p-c));

writeln('Chu vi la: ',2*p:4:2);

writeln('Dien tich la: ',s:4:2);

end

else writeln('A B C khong phai la chieu dai ba canh cua mot tam giac');

readln;

end.

a = float(input("Nhap a : "))
b = float(input("Nhap b : "))
c = float(input("Nhap c : "))
if a+b>c and a+c>b and b+c>a:
    if a==b or a==c or b==c:
        if a==c==b:
            print("Day la ba canh cua tam giac deu")
        else:
            print("Day la ba canh cua tam giac can")
    elif (a**2)+(b**2)==c**2 or (a**2)+(c**2)==b**2 or (c**2)+(b**2)==a**2:
        print("Day la ba canh cua tam giac vuong")
    else:
        pass
else:
    print("Day khong phai ba canh cua tam giac")

uses crt;

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

begin

clrscr;

repeat

write('Nhap a='); readln(a);

write('Nhap b=');c readln(b);

write('Nhap c='); readln(c);

until (a>0) and (b>0) and (c>0);

if (a+b>c) and (a+c>b) and (b+c>a) then 

begin

kt:=0;

if sqr(a)=sqr(b)+sqr(c) then kt:=1;

if sqr(b)=sqr(a)+sqr(c) then kt:=1;

if sqr(c)=sqr(a)+sqr(b) then kt:=1;

if kt=0 then writeln('Day khong la tam giac vuong')

else begin

              writeln('Day la ba canh trong mot tam giac vuong');

p:=(a+b+c)/2;

s:=sqrt(p*(p-a)*(p-b)*(p-c));

writeln('Dien tich tam giac vuong la: ',s:4:2);

end;

end

else writeln('Day khong la ba canh trong mot tam giac');

readln;

end.