Program to find roots of quadratic equations

This program uses quadratic formula to find the roots of the quadratic equations.

#include<iostream>
#include<cmath>
using namespace std;
int main(){
	double x1,x2,x3;
	double dis,r1,r2;
	cout<<"Enter the coefficients "<<endl;
	cout<<"x1 : ";
	cin>>x1;
	cout<<"x2 : ";
	cin>>x2;
	cout<<"x3 : ";
	cin>>x3;
	dis = x2*x2-4*x1*x3;
	if(dis>0){
		r1 = (-x2+sqrt(dis))/(2*x1);
		r2 = (-x2-sqrt(dis))/(2*x1);
		cout<<"r1 = "<<r1<<endl;
		cout<<"r2 = "<<r2<<endl;
	}
	else if(dis==0){
		r1 = -x2/(2*x1);
		r2 = r1;
		cout<<"r1 = r2 = "<<r1<<endl;
	}
	else{
		cout<<"Negative Roots"<<endl;
	}
	return 0;
}