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来源：牛客网

 

题目描述

In order to become a magical girl, Thinking-Bear are learning magic circle.

He first drew a regular polygon of N sides, and the length of each side is a.

He want to get a regular polygon of N sides, and the polygon area is no more than L.

He doesn't want to draw a new regular polygon as it takes too much effort.

So he think a good idea, connect the midpoint of each edge and get a new regular polygon of N sides.

How many operations does it need to get the polygon he want?

输入描述:

The first line of the input is T(1≤ T ≤ 100), which stands for the number of test cases you need to solve.The first line of each case contains three space-separated integers N, a and L (3 ≤ N ≤ 10, 1 ≤ a ≤ 100, 1 ≤ L ≤ 1000).

输出描述:

For each test case, output a single integer.

示例1

输入

复制

14 2 3

输出

复制

1

 

 

正多边形面积公式为  S=1/2*sin （2*pi/n）*n*R*R;

R = a/(   2*sin(pi/n)  )

然后，就一直更新面积啦，看需要更新几次，就是答案啦。

用公式写，复杂的也没多大啦QWQ

 

#include
    
     #include
     
      #include
      
       using namespace std;const double eps = 1e-6;#define pi acos(-1.0)int main(){	int T,sum=0;;	double N,s,a,b,L;	cin>>T;	while (T--)	{		sum=0;		cin>>N>>a>>L;		s=0.5*sin(2*pi/N)*N*(  (a/(2*sin(pi/N))  )  *   (a/(2*sin(pi/N))  )   );		while (s>L)		{			a = a * sin( (N-2) * (pi/ (N*2) )    );			s=0.5*sin(2*pi/N)*N*(  (a/(2*sin(pi/N))  )  *   (a/(2*sin(pi/N))  )   );			//cout<<"s= "<
       <