hdu1724定积分

其实是很简单的题，用定积分得到公式就行了，不过大学都毕业了我居然还会求定积分，忍不住想自夸一下^_^。。。

/*

 * hdu1724/win.cpp

 * Created on: 2012-7-6

 * Author    : ben

 */

#include <cstdio>

#include <cstdlib>

#include <cstring>

#include <cmath>

#include <ctime>

#include <iostream>

#include <algorithm>

#include <queue>

#include <set>

#include <map>

#include <stack>

#include <string>

#include <vector>

#include <deque>

#include <list>

#include <functional>

#include <numeric>

#include <cctype>

using namespace std;



double getarea(int a, int b, int L, int R) {

    double p1 = asin(R * 1.0 / a) * a * b;

    double p2 = asin(L * 1.0 / a) * a * b;

    double p3 = sqrt(a * a - R * R) * b * R / a;

    double p4 = sqrt(a * a - L * L) * b * L / a;

    return p1 - p2 + p3 - p4;

}



int main() {

#ifndef ONLINE_JUDGE

    freopen("data.in", "r", stdin);

#endif

    int T, a, b, L, R;

    scanf("%d", &T);

    while(T--) {

        double ans;

        scanf("%d%d%d%d", &a, &b, &L, &R);

        if(L >= 0) {

            ans = getarea(a, b, L, R);

        }else {

            ans = getarea(a, b, 0, R);

            ans += getarea(a, b, 0, -L);

        }

        printf("%.3f\n", ans);

    }

    return 0;

}