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Published Dec 5, 2022
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The hypot() function returns the value of the longest side of a right-angled triangle, or the hypotenuse.


hypot(x, y)

The hypotenuse is the sum of the squares of the two shorter sides of a right-angled triangle. The x and y parameters are the floating-point lengths of the other two sides.

For C++ implementations that support floating-point math:

  • The x and y parameters can be used in any order and with either sign (i.e., hypot(±x, ±y), hypot(±y, ±x)).
  • If x or y is ±0, the return value is similar to fabs() called with a non-zero argument.
  • If x or y is ±∞, then +∞ is always returned (even if the other argument is NaN).
  • Otherwise, NaN is returned if x or y is NaN.


The following example uses the hypot() function to find the hypotenuse of a right triangle with x and y values:

#include <cmath>
#include <iostream>
using namespace std;
int main() {
double x = 9, y = 10, result;
result = hypot(x, y);
cout << result << endl;
return 0;

This results in the following output:


Codebyte Example

The following example is runnable and returns the square root of the sum of squares of two long double values:


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