Java Program to Find All the Angles of a Given Triangle

Java Program to Find All the Angles of a Given Triangle

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In the previous article, we have seen Java Program to Check Whether a Given Point Lies Inside a Triangle or not

In this article we will discuss about how to find all the angles of a given triangle using Java programming language.

Java Program to Find All the Angles of a Given Triangle

Before jumping into the program directly, let’s first know how can we Find All the Angles of a Given Triangle

Explanation:

To Find All the Angles of a Given Triangle:

  • Find out the length of three sides of the triangle from the coordinates.
  • Then we will use the formula beta = acos( ( a^2 + b^2 – c^2 ) / (2ab) )
  • Convert the obtained angle from radian to degree.

Example:

Let’s see different ways to find all the angles of a given triangle.

Method-1: Java Program to Find All the Angles of a Given Triangle By Using Static Value

Approach:

  1. Declare the value for the three coordinates.
  2. Then call the angle() method by passing all 3 coordinates.
  3. Then print the result.

Program:

import java.awt.*; 
import static java.lang.Math.*; 

public class Main
{
    public static void main(String[] args)
    {
        // Static initialization of the side of the triangle
        Point a = new Point(0,0); 
        Point b = new Point(0,1); 
        Point c = new Point(1,0);
        // Calling user-defined function by passing the coordinates as parameter
        angle(a, b ,c);
    }

    // Function to find out the area of the circumcircle
    static void angle(Point A, Point B, Point C)
    {
        // Calculates the square of the sides
        int sideSquare1= calcSideSquare(A,B);
        int sideSquare2= calcSideSquare(B,C);
        int sideSquare3= calcSideSquare(C,A);

        // Calculates the length of the sides
        float side1= (float)sqrt(sideSquare1);
        float side2= (float)sqrt(sideSquare2);
        float side3= (float)sqrt(sideSquare3);

        // Calculates the angles
        float angle1= (float) acos((sideSquare2 + sideSquare3 -sideSquare1)/(2*side2*side3)); 
        float angle2= (float) acos((sideSquare1 + sideSquare3 -sideSquare2)/(2*side1*side3)); 
        float angle3= (float) acos((sideSquare1 + sideSquare2 -sideSquare3)/(2*side1*side2)); 

        // Printing the angles
        System.out.println("angle 1 : " + radianToDegree(angle1)); 
        System.out.println("angle 2 : " + radianToDegree(angle2)); 
        System.out.println("angle 3 : " + radianToDegree(angle3)); 
    }
    
    // Returns square of the sides
    static int calcSideSquare(Point p1, Point p2) 
    { 
        int xVaries = p1.x- p2.x; 
        int yVaries = p1.y- p2.y; 
        return xVaries*xVaries + yVaries*yVaries; 
    } 
    
    // Converts radian into degree
    static float radianToDegree(float rad)
    {
        float  pi = (float)3.14;
        float degree = rad * 180 / pi;
        return degree;
    }
} 

Output:

angle 1 : 45.022823
angle 2 : 90.04565
angle 3 : 45.022823

Method-2: Java Program to Find All the Angles of a Given Triangle By Using User Input Value

Approach:

  1. Take user input the value for the three coordinates.
  2. Then call the angle() method by passing all 3 coordinates.
  3. Then print the result.

Program:

import java.awt.*; 
import static java.lang.Math.PI; 
import static java.lang.Math.sqrt; 
import static java.lang.Math.acos;
import java.util.*;

public class Main
{
    public static void main(String[] args)
    {
        //Scanner class object created
        Scanner scan = new Scanner(System.in);        
        // Taking user input of the coordinates of the triangle
        System.out.println("Enter First Point Coordinates");
        Point a = new Point(scan.nextInt(),scan.nextInt()); 
        System.out.println("Enter Second Point Coordinates");
        Point b = new Point(scan.nextInt(),scan.nextInt());
        System.out.println("Enter Third Point Coordinates");
        Point c = new Point(scan.nextInt(),scan.nextInt());

        // Calling user-defined function by passing the coordinates as parameter
        angle(a, b ,c);
    }

    // Function to find out the area of the circumcircle
    static void angle(Point A, Point B, Point C)
    {
        // Calculates the square of the sides
        int sideSquare1= calcSideSquare(A,B);
        int sideSquare2= calcSideSquare(B,C);
        int sideSquare3= calcSideSquare(C,A);

        // Calculates the length of the sides
        float side1= (float)sqrt(sideSquare1);
        float side2= (float)sqrt(sideSquare2);
        float side3= (float)sqrt(sideSquare3);

        // Calculates the angles
        float angle1= (float) acos((sideSquare2 + sideSquare3 -sideSquare1)/(2*side2*side3)); 
        float angle2= (float) acos((sideSquare1 + sideSquare3 -sideSquare2)/(2*side1*side3)); 
        float angle3= (float) acos((sideSquare1 + sideSquare2 -sideSquare3)/(2*side1*side2)); 

        // Printing the angles
        System.out.println("angle 1 : " + radianToDegree(angle1)); 
        System.out.println("angle 2 : " + radianToDegree(angle2)); 
        System.out.println("angle 3 : " + radianToDegree(angle3)); 
    }
    
    // Returns square of the sides
    static int calcSideSquare(Point p1, Point p2) 
    { 
        int xVaries = p1.x- p2.x; 
        int yVaries = p1.y- p2.y; 
        return xVaries*xVaries + yVaries*yVaries; 
    } 
    
    // Converts radian into degree
    static float radianToDegree(float rad)
    {
        float  pi = (float)3.14;
        float degree = rad * 180 / pi;
        return degree;
    }
} 

Output:

Enter First Point Coordinates
0 0
Enter Second Point Coordinates
1 3
Enter Third Point Coordinates
2 0
angle 1 : 71.60135
angle 2 : 71.60135
angle 3 : 36.8886

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