Checks if a triangle is equilateral

triangle.c

#include <stdint.h>
#include <stdbool.h>
#include <math.h>
#include <stdio.h>

typedef struct {
    uint16_t x, y; 
} vector2_t; 
#define POINT(_x, _y) (vector2_t) { .x = (_x), .y = (_y) }

static inline double distance_between_points(vector2_t point1, vector2_t point2)
{
    /* 
    *        Distance formula:
    *    
    *    /-------------------------
    *   / (x2 - x1)^2 + (y2 - y1)^2
    * \/
    *
    */
    return ceil(sqrt(pow(point2.x - point1.x, 2) + pow(point2.y - point1.y, 2)));
}

bool is_equilateral_points(vector2_t point1, vector2_t point2, vector2_t point3)
{
    double  side1 = distance_between_points(point1, point2),
            side2 = distance_between_points(point2, point3),
            side3 = distance_between_points(point1, point3);

    return (side1 == side2) && (side2 == side3);
}

inline static char *bstr(bool b)
{
    return b ? "true" : "false";
}

int main()
{
    printf("%s\n", bstr(is_equilateral_points(POINT(2, 1), POINT(5, 5), POINT(7, 1))));
    printf("%s\n", bstr(is_equilateral_points(POINT(0, 2), POINT(1, 3), POINT(2, 0))));
}