小明同学喜欢体育锻炼,他常常去操场上跑步。跑道是一个圆形,在本题中,我们认为跑道是一个半径为R的圆形,设圆心的坐标原点(0,0)。小明跑步的起点坐标为(R,0),他沿着圆形跑道跑步,而且一直沿着一个方向跑步。回到家后,他查看了自己的计步器,计步器显示他跑步的总路程为L。小明想知道自己结束跑步时的坐标,但是他忘记自己是沿着顺时针方向还是逆时针方向跑的了。他想知道在这两种情况下的答案分别是多少。

include "stdafx.h"

#include<iostream>  
#include<vector>  
#include<string>
#include<math.h>
#include<iomanip>
using namespace std;


int main()
{
	float L, R;
	while (cin>>L>>R)
	{
		float len = 2 * 3.1415926*R;
		int nums = L / len;
	//	cout << "nums:" << nums << endl;
		float distance = L - nums*len;
		float jiaodu = distance / R;
	//	cout << "jiaodu" << jiaodu << endl;
		if (jiaodu <= 90)
		{
			float x1 = R*cos(jiaodu);
		//	cout << "cos(90):" << acos(90) << endl;
			float y1 = R*sin(jiaodu);
	//		cout << "x1:" << x1 << endl;
	//		cout << "y1:" << y1 << endl;

			float x2 = x1;
			float y2 = -y1;

	//		cout << "x2:" << x2 << endl;
	//		cout << "y2:" << y2 << endl;

			cout << setiosflags(ios::fixed) << setprecision(3);
			cout << x2 << " " << y2 << endl;
			cout << x1 << " " << y1 << endl;
			
		}
		else if (jiaodu > 90 && jiaodu <= 180)
		{
			float x1 = R*sin(jiaodu-90);
			float y1 = R*cos(jiaodu-90);

			float x2 = x1;
			float y2 = -y1;
			cout << setiosflags(ios::fixed) << setprecision(3);
			cout << x2 << " " << y2 << endl;
			cout << x1 << " " << y1 << endl;
		
		}
		else if (jiaodu > 180 && jiaodu <= 270)
		{
			float x1 = R*cos(jiaodu - 180);
			float y1 = R*sin(jiaodu-180);

			float x2 = x1;
			float y2 = -y1;
			cout << setiosflags(ios::fixed) << setprecision(3);
			cout << x2 << " " << y2 << endl;
			cout << x1 << " " << y1 << endl;
			

		}
		else
		{
			float x1 = R*sin(jiaodu - 270);
			float y1 = R*cos(jiaodu - 270);

			float x2 = x1;
			float y2 = -y1;
			cout << setiosflags(ios::fixed) << setprecision(3);
			cout << x2 << " " << y2 << endl;
			cout << x1 << " " << y1 << endl;
			
		}
		
		

	}

	return 0;
}
原文地址:https://www.cnblogs.com/wdan2016/p/6581177.html