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Angle between a Pair of Lines
• Difficulty Level : Medium
• Last Updated : 07 May, 2021

Given two integers M1 and M2 representing the slope of two lines intersecting at a point, the task is to find the angle between these two lines.

Examples:

Input: M1 = 1.75, M2 = 0.27
Output: 45.1455 degrees

Input: M1 = 0.5, M2 = 1.75
Output: 33.6901 degrees

Approach: If θ is the angle between the two intersecting lines, then the angle θ can be calculated by:

tanθ = |(M2 – M1) / (1 + M1 * M2)|
=> θ = tan-1( |(M2 – M1) / (1 + M1 * M2)| )

Follow the steps below to solve the problem:

Below is the implementation of the above approach:

## C++

 // C++ program for the above approach#include using namespace std; #define PI 3.14159265 // Function to find the// angle between two linesvoid findAngle(double M1, double M2){    // Store the tan value  of the angle    double angle = abs((M2 - M1)                       / (1 + M1 * M2));     // Calculate tan inverse of the angle    double ret = atan(angle);     // Convert the angle from    // radian to degree    double val = (ret * 180) / PI;     // Print the result    cout << val;} // Driver Codeint main(){    double M1 = 1.75, M2 = 0.27;     findAngle(M1, M2);     return 0;}

## Java

 // Java program for the above approachimport java.util.*;class GFG{    static double PI = 3.14159265;     // Function to find the    // angle between two lines    static void findAngle(double M1, double M2)    {               // Store the tan value  of the angle        double angle = Math.abs((M2 - M1) / (1 + M1 * M2));         // Calculate tan inverse of the angle        double ret = Math.atan(angle);         // Convert the angle from        // radian to degree        double val = (ret * 180) / PI;         // Print the result        System.out.println(val);    }     // Driver Code    public static void main(String []args)    {        double M1 = 1.75, M2 = 0.27;         findAngle(M1, M2);    }} // This code is contributed by rrrtnx.

## Python3

 # Python3 program for the above approachfrom math import atan # Function to find the# angle between two linesdef findAngle(M1, M2):    PI = 3.14159265         # Store the tan value  of the angle    angle = abs((M2 - M1) / (1 + M1 * M2))     # Calculate tan inverse of the angle    ret = atan(angle)     # Convert the angle from    # radian to degree    val = (ret * 180) / PI     # Print the result    print (round(val, 4)) # Driver Codeif __name__ == '__main__':    M1 = 1.75    M2 = 0.27     findAngle(M1, M2)     # This code is contributed by mohit kumar 29.

## C#

 // C# program for the above approachusing System;class GFG{    static double PI = 3.14159265;     // Function to find the    // angle between two lines    static void findAngle(double M1, double M2)    {               // Store the tan value  of the angle        double angle = Math.Abs((M2 - M1) / (1 + M1 * M2));         // Calculate tan inverse of the angle        double ret = Math.Atan(angle);         // Convert the angle from        // radian to degree        double val = (ret * 180) / PI;         // Print the result        Console.Write(val);    }     // Driver Code    public static void Main()    {        double M1 = 1.75, M2 = 0.27;         findAngle(M1, M2);    }} // This code is contributed by ukasp.

## Javascript


Output:
45.1455

Time Complexity: O(1)
Auxiliary Space: O(1)

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