UVA 12901 Refraction 数学

题目链接：http://acm.hust.edu.cn/vjudge/contest/view.action?cid=83008#problem/E

Description

HINT

题意：

给你一个水池，水池中放一个东西，上面一双眼睛，问眼睛能看到东西时，水面的最小高度

题解：

列列方程就是了

 #include <cstdio>
 #include <cmath>
 #include <cstring>
 #include <ctime>
 #include <iostream>
 #include <algorithm>
 #include <set>
 #include <vector>
 #include <sstream>
 #include <queue>
 #include <typeinfo>
 #include <fstream>
 #include <map>
 #include <stack>
 typedef long long ll;
 using namespace std;
 //freopen("D.in","r",stdin);
 //freopen("D.out","w",stdout);
 #define sspeed ios_base::sync_with_stdio(0);cin.tie(0)
 #define test freopen("test.txt","r",stdin)
 #define maxn 2000001
 #define mod 1000000007
 #define eps 1e-9
 const int inf=0x3f3f3f3f;
 const ll infll = 0x3f3f3f3f3f3f3f3fLL;
 inline ll read()
 {
     ll x=,f=;char ch=getchar();
     while(ch<''||ch>''){if(ch=='-')f=-;ch=getchar();}
     while(ch>=''&&ch<=''){x=x*+ch-'';ch=getchar();}
     return x*f;
 }
 //**************************************************************************************

 double w,h,x,xe,ye,p;

 int main()
 {
     int t=read();
     while(t--)
     {
         cin>>w>>h>>x>>xe>>ye>>p;
         double tan1=(xe-w)/(ye-h);
         double tan2=tan(asin(sin(atan(tan1))/p));

         double x1=w-tan1*h;
         double ans=(x-x1)/(tan1-tan2);
         if(ans<=)
             cout<<"0.0000"<<endl;
         else if(ans>h)
             cout<<"Impossible"<<endl;
         else
             printf("%.4f\n",ans);
     }
 }