夹角的问题-题解(C语言代码)

#include <stdio.h>
#include <math.h>
int main(void)
{
    double x1 = 0.0, y1 = 0.0, x2 = 0.0, y2 = 0.0, v1 = 0.0, v2 = 0.0;
    int N = 0;
    scanf("%d", &N);
    while (N--) {
        scanf("%lf %lf %lf %lf", &x1, &y1, &x2, &y2);
        v1 = x1/sqrt(x1*x1+y1*y1), v2 = x2/sqrt(x2*x2+y2*y2);
        v1 = acos(v1)/3.1415926*180, v2 = acos(v2)/3.1415926*180;
        if (v1 > v2) printf("%.2lf\n", v1-v2);
        else printf("%.2lf\n", v2-v1);
    }
}