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Check whether two straight lines are orthogonal or not

  • Difficulty Level : Basic
  • Last Updated : 11 May, 2021

Given two line segments AB and CD having A(x1, y1), B(x2, y2), C(x3, y3) and D(x4, y4). The task is to check whether these two lines are orthogonal or not. Two lines are called orthogonal if they are perpendicular at the point of intersection.
 

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Examples: 
 

Input: x1 = 0, y1 = 3, x2 = 0, y2 = -5
        x3 = 2, y3 = 0, x4 = -1, y4 = 0
Output: Yes

Input:  x1 = 0, y1 = 4, x2 = 0, y2 = -9
        x3 = 2, y3 = 0, x4 = -1, y4 = 0
Output: Yes

 



Approach: If the slopes of the two lines are m1 and m2 then for them to be orthogonal we need to check if: 
 

  • Both lines have infinite slope then answer is no.
  • One line has infinite slope and if other line has 0 slope then answer is yes otherwise no.
  • Both lines have finite slope and their product is -1 then the answer is yes.

Below is the implementation of the above approach:
 

C++




// C++ implementation of above approach
#include <bits/stdc++.h>
using namespace std;
 
// Function to check if two straight
// lines are orthogonal or not
bool checkOrtho(int x1, int y1, int x2, int y2,
                int x3, int y3, int x4, int y4)
{
 
    int m1, m2;
 
    // Both lines have infinite slope
    if (x2 - x1 == 0 && x4 - x3 == 0)
        return false;
 
    // Only line 1 has infinite slope
    else if (x2 - x1 == 0) {
 
        m2 = (y4 - y3) / (x4 - x3);
 
        if (m2 == 0)
            return true;
        else
            return false;
    }
 
    // Only line 2 has infinite slope
    else if (x4 - x3 == 0) {
 
        m1 = (y2 - y1) / (x2 - x1);
 
        if (m1 == 0)
            return true;
        else
            return false;
    }
 
    else {
        // Find slopes of the lines
        m1 = (y2 - y1) / (x2 - x1);
        m2 = (y4 - y3) / (x4 - x3);
 
        // Check if their product is -1
        if (m1 * m2 == -1)
            return true;
        else
            return false;
    }
}
 
// Driver code
int main()
{
    int x1 = 0, y1 = 4, x2 = 0, y2 = -9;
    int x3 = 2, y3 = 0, x4 = -1, y4 = 0;
 
    checkOrtho(x1, y1, x2, y2, x3, y3, x4, y4) ? cout << "Yes"
                                               : cout << "No";
 
    return 0;
}

Java




//Java implementation of above approach
 
import java.io.*;
 
class GFG {
     
    // Function to check if two straight
    // lines are orthogonal or not
    static boolean checkOrtho(int x1, int y1, int x2, int y2,
                    int x3, int y3, int x4, int y4)
    {
 
        int m1, m2;
     
        // Both lines have infinite slope
        if (x2 - x1 == 0 && x4 - x3 == 0)
            return false;
 
        // Only line 1 has infinite slope
        else if (x2 - x1 == 0)
        {
            m2 = (y4 - y3) / (x4 - x3);
            if (m2 == 0)
                return true;
            else
                return false;
        }
 
        // Only line 2 has infinite slope
        else if (x4 - x3 == 0)
        {
             m1 = (y2 - y1) / (x2 - x1);
            if (m1 == 0)
                return true;
            else
                return false;
        }
 
        else
        {
            // Find slopes of the lines
            m1 = (y2 - y1) / (x2 - x1);
            m2 = (y4 - y3) / (x4 - x3);
 
            // Check if their product is -1
            if (m1 * m2 == -1)
                return true;
            else
                return false;
        }
    }
 
    // Driver code
    public static void main (String[] args)
    {
        int x1 = 0, y1 = 4, x2 = 0, y2 = -9;
        int x3 = 2, y3 = 0, x4 = -1, y4 = 0;
 
        if(checkOrtho(x1, y1, x2, y2, x3, y3, x4, y4)==true)
            System.out.println ("Yes");
        else
            System.out.println("No" );
    }
}
 
//This code is contributed by akt_mit..

Python3




# Python 3 implementation of above approach
 
# Function to check if two straight
# lines are orthogonal or not
def checkOrtho(x1, y1, x2, y2, x3, y3, x4, y4):
     
    # Both lines have infinite slope
    if (x2 - x1 == 0 and x4 - x3 == 0):
        return False
 
    # Only line 1 has infinite slope
    elif (x2 - x1 == 0):
        m2 = (y4 - y3) / (x4 - x3)
 
        if (m2 == 0):
            return True
        else:
            return False
 
    # Only line 2 has infinite slope
    elif (x4 - x3 == 0):
        m1 = (y2 - y1) / (x2 - x1);
 
        if (m1 == 0):
            return True
        else:
            return False
 
    else:
         
        # Find slopes of the lines
        m1 = (y2 - y1) / (x2 - x1)
        m2 = (y4 - y3) / (x4 - x3)
 
        # Check if their product is -1
        if (m1 * m2 == -1):
            return True
        else:
            return False
     
# Driver code
if __name__ == '__main__':
    x1 = 0
    y1 = 4
    x2 = 0
    y2 = -9
    x3 = 2
    y3 = 0
    x4 = -1
    y4 = 0
     
    if(checkOrtho(x1, y1, x2, y2,
                  x3, y3, x4, y4)):
        print("Yes")
    else:
        print("No")
 
# This code is contributed by
# Shashank_Sharma

C#




// C# implementation of above approach
using System;
 
class GFG
{
     
    // Function to check if two straight
    // lines are orthogonal or not
    static bool checkOrtho(int x1, int y1, int x2, int y2,
                    int x3, int y3, int x4, int y4)
    {
 
        int m1, m2;
     
        // Both lines have infinite slope
        if (x2 - x1 == 0 && x4 - x3 == 0)
            return false;
 
        // Only line 1 has infinite slope
        else if (x2 - x1 == 0)
        {
            m2 = (y4 - y3) / (x4 - x3);
            if (m2 == 0)
                return true;
            else
                return false;
        }
 
        // Only line 2 has infinite slope
        else if (x4 - x3 == 0)
        {
            m1 = (y2 - y1) / (x2 - x1);
            if (m1 == 0)
                return true;
            else
                return false;
        }
 
        else
        {
            // Find slopes of the lines
            m1 = (y2 - y1) / (x2 - x1);
            m2 = (y4 - y3) / (x4 - x3);
 
            // Check if their product is -1
            if (m1 * m2 == -1)
                return true;
            else
                return false;
        }
    }
 
    // Driver code
    public static void Main ()
    {
        int x1 = 0, y1 = 4, x2 = 0, y2 = -9;
        int x3 = 2, y3 = 0, x4 = -1, y4 = 0;
 
        if(checkOrtho(x1, y1, x2, y2, x3, y3, x4, y4) == true)
            Console.WriteLine("Yes");
        else
            Console.WriteLine("No" );
    }
}
 
// This code is contributed by Ryuga

PHP




<?php
// PHP implementation of above approach
 
// Function to check if two straight
// lines are orthogonal or not
function checkOrtho($x1, $y1, $x2, $y2,
                    $x3, $y3, $x4, $y4)
{
 
    // Both lines have infinite slope
    if ($x2 - $x1 == 0 && $x4 - $x3 == 0)
        return false;
 
    // Only line 1 has infinite slope
    else if ($x2 - $x1 == 0)
    {
        $m2 = (int)(($y4 - $y3) / ($x4 - $x3));
 
        if ($m2 == 0)
            return true;
        else
            return false;
    }
 
    // Only line 2 has infinite slope
    else if ($x4 - $x3 == 0)
    {
        $m1 = (int)(($y2 - $y1) / ($x2 - $x1));
 
        if ($m1 == 0)
            return true;
        else
            return false;
    }
 
    else
    {
         
        // Find slopes of the lines
        $m1 = (int)(($y2 - $y1) / ($x2 - $x1));
        $m2 = (int)(($y4 - $y3) / ($x4 - $x3));
 
        // Check if their product is -1
        if ($m1 * $m2 == -1)
            return true;
        else
            return false;
    }
}
 
// Driver code
$x1 = 0; $y1 = 4;
$x2 = 0; $y2 = -9;
$x3 = 2; $y3 = 0;
$x4 = -1; $y4 = 0;
 
if(checkOrtho($x1, $y1, $x2, $y2,
              $x3, $y3, $x4, $y4))
    print("Yes");
else
    print("No");
 
// This code is contributed by chandan_jnu
?>

Javascript




<script>
    // Javascript implementation of above approach
     
    // Function to check if two straight
    // lines are orthogonal or not
    function checkOrtho(x1, y1, x2, y2, x3, y3, x4, y4)
    {
   
        let m1, m2;
       
        // Both lines have infinite slope
        if (x2 - x1 == 0 && x4 - x3 == 0)
            return false;
   
        // Only line 1 has infinite slope
        else if (x2 - x1 == 0)
        {
            m2 = parseInt((y4 - y3) / (x4 - x3), 10);
            if (m2 == 0)
                return true;
            else
                return false;
        }
   
        // Only line 2 has infinite slope
        else if (x4 - x3 == 0)
        {
            m1 = parseInt((y2 - y1) / (x2 - x1), 10);
            if (m1 == 0)
                return true;
            else
                return false;
        }
   
        else
        {
            // Find slopes of the lines
            m1 = parseInt((y2 - y1) / (x2 - x1), 10);
            m2 = parseInt((y4 - y3) / (x4 - x3), 10);
   
            // Check if their product is -1
            if (m1 * m2 == -1)
                return true;
            else
                return false;
        }
    }
     
    let x1 = 0, y1 = 4, x2 = 0, y2 = -9;
    let x3 = 2, y3 = 0, x4 = -1, y4 = 0;
 
    if(checkOrtho(x1, y1, x2, y2, x3, y3, x4, y4) == true)
      document.write("Yes");
    else
      document.write("No" );
 
</script>
Output: 
Yes

 




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