Angle between a Pair of Lines (original) (raw)

Last Updated : 23 Jul, 2025

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 ? is the angle between the two intersecting lines, then the angle ? can be calculated by:

tan? = |(M2 - M1) / (1 + M1 * M2)|
=> ? = tan-1( |(M2 - M1) / (1 + M1 * M2)| )

Follow the steps below to solve the problem:

• Initialize a variable, say A, to store the value of the angle between the two lines.
• Using the above formula, find the value of tan(A)and update the value of angle A by taking the tan inverse of the angle.
• Convert the angle from radian to degrees.
• Print the value of A in degrees as the result.

Below is the implementation of the above approach:

C++ `

// C++ program for the above approach #include <bits/stdc++.h> using namespace std;

#define PI 3.14159265

// Function to find the // angle between two lines void 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 Code int main() { double M1 = 1.75, M2 = 0.27;

findAngle(M1, M2);

return 0;

}

Java

// Java program for the above approach import 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 approach

from math import atan

Function to find the

angle between two lines

def 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 Code

if 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 approach using 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

`

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