P4710 平抛运动

　　题目：https://www.luogu.org/problemnew/show/P4710

$$ v_x = v_{x_0} = v \ sin \ \theta, \  v_y = v_{y_0} + gt = gt = v \ cos \ \theta, \ 这里 v_y = gt \Rightarrow t = \frac{v_y}{g} $$

$$ \left \{ \begin{aligned} x &= v_x t \\ y &= \frac{1}{2}gt^2 = \frac{1}{2}v_yt \end{aligned} \right. $$

　　于是，AC代码：

#include <bits/stdc++.h>
int main()
{
	double v, vy, theta;
	double x, y, t;

	scanf("%lf %lf", &v, &theta);
	vy = v*cos(theta);
	t = vy/10.0;
	x = v*sin(theta)*t;
	y = (vy*t)/2.0;
	printf("%f %f\n", x, y);
	return 0;
}