#描述#
As the graph you see below, we named the red part "RedField".<br>
<img src="../Images/RedField.jpg"><br>
The read part is the intersection of an ellipse and a triangle.Now, 8600's not good at math, so he wants you to help him calculate the area of the "RedField".

#格式#
##输入格式##
The first line of input contains n, the number of test cases. n lines follow.Each test case contains four numbers a, b, x, y(0 &lt b &lt= a &lt= x),and a is the length of OA, b is the length of OB,and x, y representing the coordinate of the point P.

##输出格式##
For each test case, output the area of the "RedField",accurate up to 2 decimal places.

#样例1#
##样例输入1##

1
1.00 1.00 2.00 2.00

##样例输出1##

0.39

#限制#
1000ms
32768KB

#提示#

#来源#