RefractionI
Refraction is a common phenomena in our life. Now ,comes a problem. Give you a kind of liquid and its refractive index,you should calculate the focus of the light on the ground (Point T in the picture below). To let the problem easier,we assume that the air`s refractive index is always 1. As the picture below,the light source isalways in the air(the point S in the picture). We assume the Y coordinate of ground level is 0.
Input
The first line of the data contains a number T(1<=T<=500), indicating the total number of test cases. Each test case consists of 2 lines .The first line contains 4 numer x1,y1,x2,y2, indicating the coordinate of the light and the coordinate of the direction respectively. The second line contains 2 numbers n,H,indicating the refractive index of the liquid and the deepth of the liquid.
Output
For each test case, write a single float numbers x on a single line, indicating the X coordinate of the focus,retain 3 digits after the decimal point.
If there is not focus on the ground ,just output “Impossible” on a single line.
If there is not focus on the ground ,just output “Impossible” on a single line.
Sample Input
3
3 6 0 6
1.35 3
3 6 0 3
1.35 3
3 6 3 3
1.35 3
Sample Output
Impossible
-1.845
3.000