HYPOT

hypot − Euclidean distance function

#include <math.h>

double hypot(double x, double y);

The hypot() function returns the sqrt(x*x + y*y). This is the length of the hypotenuse of a right-angle triangle with sides of length x and y, or the distance of the point (x, y) from the origin.

SVID 3, BSD 4.3

sqrt(3)