Check if given two straight lines are identical or not

Given two straight lines with co-efficients of there equations **a1x + b1y + c1 = 0** and **a2x + b2y + c2 = 0** respectively, the task is to check if the straight lines are identical or not. **Examples:**

Input:a1 = -2, b1 = 4, c1 = 3, a2 = -6, b2 = 12, c2 = 9Output:The given straight lines are identicalInput:a1 = 12, b1 = 3, c1 = 8, a2 = 7, b2 = -12, c2 = 0Output:The given straight lines are not identical

**Approach**:

- Given equations,
**a1x + b1y + c1 = 0****a2x + b2y + c2 = 0**

- converting them to slope intercept form, we get
**y = (-a1/b1)x +(-c1/b1)****y = (-a2/b2)x +(-c2/b2)**

- now, if the lines are identical then there slope and intercepts must be equal,

so,**-a1/b1 = -a2/b2****or, a1/a2 = b1/b2**

also,**-c1/b1 = -c2/b2****so, c1/c2 = b1/b2**

- So, if two given straight lines are identical then there co-efficients should be proportional.

**Below is the implementation of the above approach**

## C++

`// C++ program to check if` `// given two straight lines` `// are identical or not` `#include <bits/stdc++.h>` `using` `namespace` `std;` `// Function to check if they are identical` `void` `idstrt(` `double` `a1, ` `double` `b1,` ` ` `double` `c1, ` `double` `a2,` ` ` `double` `b2, ` `double` `c2)` `{` ` ` `if` `((a1 / a2 == b1 / b2)` ` ` `&& (a1 / a2 == c1 / c2)` ` ` `&& (b1 / b2 == c1 / c2))` ` ` `cout << ` `"The given straight"` ` ` `<< ` `" lines are identical"` ` ` `<< endl;` ` ` `else` ` ` `cout << ` `"The given straight"` ` ` `<< ` `" lines are not identical"` ` ` `<< endl;` `}` `// Driver Code` `int` `main()` `{` ` ` `double` `a1 = -2, b1 = 4,` ` ` `c1 = 3, a2 = -6,` ` ` `b2 = 12, c2 = 9;` ` ` `idstrt(a1, b1, c1, a2, b2, c2);` ` ` `return` `0;` `}` |

## Java

`// Java program to check if` `// given two straight lines` `// are identical or not` `class` `GFG` `{` `// Function to check if they are identical` `static` `void` `idstrt(` `double` `a1, ` `double` `b1,` ` ` `double` `c1, ` `double` `a2,` ` ` `double` `b2, ` `double` `c2)` `{` ` ` `if` `((a1 / a2 == b1 / b2)` ` ` `&& (a1 / a2 == c1 / c2)` ` ` `&& (b1 / b2 == c1 / c2))` ` ` `System.out.println( ` `"The given straight"` ` ` `+` `" lines are identical"` `);` ` ` `else` ` ` `System.out.println(` `"The given straight"` ` ` `+ ` `" lines are not identical"` `);` `}` `// Driver Code` `public` `static` `void` `main(String[] args)` `{` ` ` `double` `a1 = -` `2` `, b1 = ` `4` `,` ` ` `c1 = ` `3` `, a2 = -` `6` `,` ` ` `b2 = ` `12` `, c2 = ` `9` `;` ` ` `idstrt(a1, b1, c1, a2, b2, c2);` `}` `}` `// This code has been contributed by 29AjayKumar` |

## Python3

`# Python3 program to check if` `# given two straight lines` `# are identical or not` `# Function to check if they are identical` `def` `idstrt(a1, b1, c1, a2, b2, c2):` ` ` `if` `((a1 ` `/` `/` `a2 ` `=` `=` `b1 ` `/` `/` `b2) ` `and` ` ` `(a1 ` `/` `/` `a2 ` `=` `=` `c1 ` `/` `/` `c2) ` `and` ` ` `(b1 ` `/` `/` `b2 ` `=` `=` `c1 ` `/` `/` `c2)):` ` ` `print` `(` `"The given straight lines"` `,` ` ` `"are identical"` `);` ` ` `else` `:` ` ` `print` `(` `"The given straight lines"` `,` ` ` `"are not identical"` `);` `# Driver Code` `a1, b1 ` `=` `-` `2` `, ` `4` `c1, a2 ` `=` `3` `,` `-` `6` `b2, c2 ` `=` `12` `,` `9` `idstrt(a1, b1, c1, a2, b2, c2)` `# This code is contributed` `# by mohit kumar` |

## C#

`// C# program to check if` `// given two straight lines` `// are identical or not` `using` `System;` `class` `GFG` `{` `// Function to check if they are identical` `static` `void` `idstrt(` `double` `a1, ` `double` `b1,` ` ` `double` `c1, ` `double` `a2,` ` ` `double` `b2, ` `double` `c2)` `{` ` ` `if` `((a1 / a2 == b1 / b2)` ` ` `&& (a1 / a2 == c1 / c2)` ` ` `&& (b1 / b2 == c1 / c2))` ` ` `Console.WriteLine( ` `"The given straight"` ` ` `+` `" lines are identical"` `);` ` ` `else` ` ` `Console.WriteLine(` `"The given straight"` ` ` `+ ` `" lines are not identical"` `);` `}` `// Driver Code` `public` `static` `void` `Main(String[] args)` `{` ` ` `double` `a1 = -2, b1 = 4,` ` ` `c1 = 3, a2 = -6,` ` ` `b2 = 12, c2 = 9;` ` ` `idstrt(a1, b1, c1, a2, b2, c2);` `}` `}` `// This code contributed by Rajput-Ji` |

## PHP

`<?php` `// PHP program to check if` `// given two straight lines` `// are identical or not` `// Function to check if they are identical` `function` `idstrt(` `$a1` `, ` `$b1` `,` ` ` `$c1` `, ` `$a2` `,` ` ` `$b2` `, ` `$c2` `)` `{` ` ` `if` `((` `$a1` `/ ` `$a2` `== ` `$b1` `/ ` `$b2` `)` ` ` `&& (` `$a1` `/ ` `$a2` `== ` `$c1` `/ ` `$c2` `)` ` ` `&& (` `$b1` `/ ` `$b2` `== ` `$c1` `/ ` `$c2` `))` ` ` `echo` `"The given straight lines are identical"` `,` `"\n"` `;` ` ` `else` ` ` `echo` `"The given straight lines are not identical"` `,` `"\n"` `;` `}` ` ` `// Driver Code` ` ` `$a1` `= -2; ` `$b1` `= 4;` ` ` `$c1` `= 3; ` `$a2` `= -6;` ` ` `$b2` `= 12; ` `$c2` `= 9;` ` ` `idstrt(` `$a1` `, ` `$b1` `, ` `$c1` `, ` `$a2` `, ` `$b2` `, ` `$c2` `);` ` ` `// This code is contributed by Ryuga` `?>` |

## Javascript

`<script>` `// javascript program to check if` `// given two straight lines` `// are identical or not` `// Function to check if they are identical` `function` `idstrt(a1 , b1,` ` ` `c1 , a2,` ` ` `b2 , c2)` `{` ` ` `if` `((a1 / a2 == b1 / b2)` ` ` `&& (a1 / a2 == c1 / c2)` ` ` `&& (b1 / b2 == c1 / c2))` ` ` `document.write( ` `"The given straight"` ` ` `+` `" lines are identical"` `);` ` ` `else` ` ` `document.write(` `"The given straight"` ` ` `+ ` `" lines are not identical"` `);` `}` `// Driver Code` ` ` `var` `a1 = -2, b1 = 4,` ` ` `c1 = 3, a2 = -6,` ` ` `b2 = 12, c2 = 9;` `idstrt(a1, b1, c1, a2, b2, c2);` `// This code contributed by Princi Singh` `</script>` |

**Output:**

The given straight lines are identical

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the **DSA Self Paced Course** at a student-friendly price and become industry ready.