H

高中物理 分两种情况，具体看代码。

using namespace std;
double r, d, v, a, o;

int main(void)
{
    cin >> r >> d >> v >> a >> o;
    double h = r * cos(o);
    if (d <= h)//图1的情况
    {
        double l = r * asin(d / r);
        double L = 0, R = 10000;

        for (int i = 1; i <= 100; i++)//解一元二次方程,二分答案
        {
            double mid = (L + R) / 2;
            if (0.50000 * a * mid * mid + v * mid - l < 0)L = mid;
            else R = mid;
        }
        printf("%.10lf", L );
    }
    else//图2的情况
    {
        double o1 = asin(d / r);
        double o2 = asin(h / r);
        double t1 = (o1 - o2) * r / v;//匀速时间

        double l = r * asin(h / r);
        double L = 0, R = 10000;

        for (int i = 1; i <= 100; i++)
        {
            double mid = (L + R) / 2;
            if (0.50000 * a * mid * mid + v * mid - l < 0)L = mid;
            else R = mid;
        }
        printf("%.10lf",L+t1);
    }
    return 0;

}