Skip to content
Related Articles

Related Articles

Find all sides of a right angled triangle from given hypotenuse and area | Set 1
  • Difficulty Level : Medium
  • Last Updated : 26 Mar, 2021
GeeksforGeeks - Summer Carnival Banner

Given hypotenuse and area of a right angle triangle, get its base and height and if any triangle with given hypotenuse and area is not possible, print not possible.
Examples: 
 

Input  : hypotenuse = 5,    area = 6
Output : base = 3, height = 4

Input : hypotenuse = 5, area = 7 
Output : No triangle possible with above specification.

 

hypotenuse

 

We can use a property of right angle triangle for solving this problem, which can be stated as follows, 
 



A right angle triangle with fixed hypotenuse attains
maximum area, when it is isosceles i.e. both height
and base becomes equal so if hypotenuse if H, then 
by pythagorean theorem,
Base2 + Height2 = H2

For maximum area both base and height should be equal, 
b2 + b2 = H2
b = sqrt(H2/2)

Above is the length of base at which triangle attains
maximum area, given area must be less than this maximum
area, otherwise no such triangle will possible.  

Now if given area is less than this maximum area, we can do a binary search for length of base, as increasing base will increases area, it is a monotonically increasing function where binary search can be applied easily. 
In below code, a method is written for getting area of right angle triangle, recall that for right angle triangle area is ½*base*height and height can be calculated from base and hypotenuse using pythagorean theorem.
Below is the implementation of above approach:
 

C++




// C++ program to get right angle triangle, given
// hypotenuse and area of triangle
#include <bits/stdc++.h>
using namespace std;
   
//  limit for float comparison
#define eps 1e-6
   
// Utility method to get area of right angle triangle,
// given base and hypotenuse
double getArea(double base, double hypotenuse)
{
    double height = sqrt(hypotenuse*hypotenuse - base*base);
    return 0.5 * base * height;
}
   
// Prints base and height of triangle using hypotenuse
// and area information
void printRightAngleTriangle(int hypotenuse, int area)
{
    int hsquare = hypotenuse * hypotenuse;
   
    // maximum area will be obtained when base and height
    // are equal (= sqrt(h*h/2))
    double sideForMaxArea = sqrt(hsquare / 2.0);
    double maxArea = getArea(sideForMaxArea, hypotenuse);
   
    // if given area itself is larger than maxArea then no
    // solution is possible
    if (area > maxArea)
    {
        cout << "Not possiblen";
        return;
    }
   
    double low = 0.0;
    double high = sideForMaxArea;
    double base;
   
    // binary search for base
    while (abs(high - low) > eps)
    {
        base = (low + high) / 2.0;
        if (getArea(base, hypotenuse) >= area)
            high = base;
        else
            low = base;
    }
   
    // get height by pythagorean rule
    double height = sqrt(hsquare - base*base);
    cout << base << " " << height << endl;
}
   
// Driver code to test above methods
int main()
{
    int hypotenuse = 5;
    int area = 6;
   
    printRightAngleTriangle(hypotenuse, area);
    return 0;
}

Java




// Java program to get right angle triangle, given
// hypotenuse and area of triangle
public class GFG {
 
// limit for float comparison
    final static double eps = (double) 1e-6;
 
// Utility method to get area of right angle triangle,
// given base and hypotenuse
    static double getArea(double base, double hypotenuse) {
        double height = Math.sqrt(hypotenuse * hypotenuse - base * base);
        return 0.5 * base * height;
    }
 
// Prints base and height of triangle using hypotenuse
// and area information
    static void printRightAngleTriangle(int hypotenuse, int area) {
        int hsquare = hypotenuse * hypotenuse;
 
        // maximum area will be obtained when base and height
        // are equal (= sqrt(h*h/2))
        double sideForMaxArea = Math.sqrt(hsquare / 2.0);
        double maxArea = getArea(sideForMaxArea, hypotenuse);
 
        // if given area itself is larger than maxArea then no
        // solution is possible
        if (area > maxArea) {
            System.out.print("Not possible");
            return;
        }
 
        double low = 0.0;
        double high = sideForMaxArea;
        double base = 0;
 
        // binary search for base
        while (Math.abs(high - low) > eps) {
            base = (low + high) / 2.0;
            if (getArea(base, hypotenuse) >= area) {
                high = base;
            } else {
                low = base;
            }
        }
 
        // get height by pythagorean rule
        double height = Math.sqrt(hsquare - base * base);
        System.out.println(Math.round(base) + " " + Math.round(height));
    }
 
// Driver code to test above methods
    static public void main(String[] args) {
        int hypotenuse = 5;
        int area = 6;
 
        printRightAngleTriangle(hypotenuse, area);
    }
}
 
// This code is contributed by 29AjayKumar

Python3




# Python 3 program to get right angle triangle, given
# hypotenuse and area of triangle
 
# limit for float comparison
# define eps 1e-6
import math
 
# Utility method to get area of right angle triangle,
# given base and hypotenuse
def getArea(base, hypotenuse):
    height = math.sqrt(hypotenuse*hypotenuse - base*base);
    return 0.5 * base * height
 
# Prints base and height of triangle using hypotenuse
# and area information
def printRightAngleTriangle(hypotenuse, area):
    hsquare = hypotenuse * hypotenuse
 
    # maximum area will be obtained when base and height
    # are equal (= sqrt(h*h/2))
    sideForMaxArea = math.sqrt(hsquare / 2.0)
    maxArea = getArea(sideForMaxArea, hypotenuse)
 
    # if given area itself is larger than maxArea then no
    # solution is possible
    if (area > maxArea):
        print("Not possiblen")
        return
     
    low = 0.0
    high = sideForMaxArea
     
    # binary search for base
    while (abs(high - low) > 1e-6):
        base = (low + high) / 2.0
        if (getArea(base, hypotenuse) >= area):
            high =base
        else:
            low = base
     
    # get height by pythagorean rule
    height = math.ceil(math.sqrt(hsquare - base*base))
    base = math.floor(base)
    print(base,height)
 
# Driver code to test above methods
if __name__ == '__main__':
    hypotenuse = 5
    area = 6
 
    printRightAngleTriangle(hypotenuse, area)
 
# This code is contributed by
# Surendra_Gangwar

C#




// C# program to get right angle triangle, given
// hypotenuse and area of triangle
 
using System;
public class GFG{
 
 
// limit for float comparison
     static double eps = (double) 1e-6;
 
// Utility method to get area of right angle triangle,
// given base and hypotenuse
    static double getArea(double base1, double hypotenuse) {
        double height = Math.Sqrt(hypotenuse * hypotenuse - base1 * base1);
        return 0.5 * base1 * height;
    }
 
// Prints base and height of triangle using hypotenuse
// and area information
    static void printRightAngleTriangle(int hypotenuse, int area) {
        int hsquare = hypotenuse * hypotenuse;
 
        // maximum area will be obtained when base and height
        // are equal (= sqrt(h*h/2))
        double sideForMaxArea = Math.Sqrt(hsquare / 2.0);
        double maxArea = getArea(sideForMaxArea, hypotenuse);
 
        // if given area itself is larger than maxArea then no
        // solution is possible
        if (area > maxArea) {
            Console.Write("Not possible");
            return;
        }
 
        double low = 0.0;
        double high = sideForMaxArea;
        double base1 = 0;
 
        // binary search for base
        while (Math.Abs(high - low) > eps) {
            base1 = (low + high) / 2.0;
            if (getArea(base1, hypotenuse) >= area) {
                high = base1;
            } else {
                low = base1;
            }
        }
 
        // get height by pythagorean rule
        double height = Math.Sqrt(hsquare - base1 * base1);
        Console.WriteLine(Math.Round(base1) + " " + Math.Round(height));
    }
 
// Driver code to test above methods
    static public void Main() {
        int hypotenuse = 5;
        int area = 6;
 
        printRightAngleTriangle(hypotenuse, area);
    }
}
 
// This code is contributed by 29AjayKumar

PHP




<?php
// PHP program to get right angle triangle,
// given hypotenuse and area of triangle
 
// limit for float comparison
$eps =.0000001;
 
// Utility method to get area of right
// angle triangle, given base and hypotenuse
function getArea($base, $hypotenuse)
{
    $height = sqrt($hypotenuse * $hypotenuse -
                                 $base * $base);
    return 0.5 * $base * $height;
}
 
// Prints base and height of triangle
// using hypotenuse and area information
function printRightAngleTriangle($hypotenuse,
                                 $area)
{
    global $eps;
    $hsquare = $hypotenuse * $hypotenuse;
 
    // maximum area will be obtained when base
    // and height are equal (= sqrt(h*h/2))
    $sideForMaxArea = sqrt($hsquare / 2.0);
    $maxArea = getArea($sideForMaxArea,
                       $hypotenuse);
 
    // if given area itself is larger than
    // maxArea then no solution is possible
    if ($area > $maxArea)
    {
        echo "Not possiblen";
        return;
    }
 
    $low = 0.0;
    $high = $sideForMaxArea;
    $base;
 
    // binary search for base
    while (abs($high - $low) > $eps)
    {
        $base = ($low + $high) / 2.0;
        if (getArea($base, $hypotenuse) >= $area)
            $high = $base;
        else
            $low = $base;
    }
 
    // get height by pythagorean rule
    $height = sqrt($hsquare - $base * $base);
        echo (ceil($base)) ," ",
             (floor($height)), "\n";
}
 
// Driver Code
$hypotenuse = 5;
$area = 6;
 
printRightAngleTriangle($hypotenuse, $area);
 
// This code is contributed by Sachin
?>

Javascript




<script>
 
// JavaScript program to get right angle triangle, given
// hypotenuse and area of triangle
 
// limit for float comparison
    let eps =  1e-6;
   
// Utility method to get area of right angle triangle,
// given base and hypotenuse
    function getArea(base, hypotenuse) {
        let height = Math.sqrt(hypotenuse * hypotenuse - base * base);
        return 0.5 * base * height;
    }
   
// Prints base and height of triangle using hypotenuse
// and area information
    function printRightAngleTriangle(hypotenuse, area) {
        let hsquare = hypotenuse * hypotenuse;
   
        // maximum area will be obtained when base and height
        // are equal (= sqrt(h*h/2))
        let sideForMaxArea = Math.sqrt(hsquare / 2.0);
        let maxArea = getArea(sideForMaxArea, hypotenuse);
   
        // if given area itself is larger than maxArea then no
        // solution is possible
        if (area > maxArea) {
            document.write("Not possible");
            return;
        }
   
        let low = 0.0;
        let high = sideForMaxArea;
        let base = 0;
   
        // binary search for base
        while (Math.abs(high - low) > eps) {
            base = (low + high) / 2.0;
            if (getArea(base, hypotenuse) >= area) {
                high = base;
            } else {
                low = base;
            }
        }
   
        // get height by pythagorean rule
        let height = Math.sqrt(hsquare - base * base);
        document.write(Math.round(base) + " " + Math.round(height));
    }
     
// Driver Code
        let hypotenuse = 5;
         let area = 6;
   
        printRightAngleTriangle(hypotenuse, area);
 
// This code is contributed by chinmoy1997pal.
</script>

Output: 
 

3 4

One more solution is discussed in below post. 
Check if right angles possible from given area and hypotenuse
This article is contributed by Utkarsh Trivedi. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.
 

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.

My Personal Notes arrow_drop_up
Recommended Articles
Page :