Largest inscribed rectangle

A rectangle is inscribed in a circle of radius $R$ when all four of its corners lie on the circle. Find the largest area of an inscribed rectangle whose shorter side is at most $B$. A square counts as a rectangle.

The first line contains an integer $T$, the number of test cases ($1 \le T \le 1000$). Each of the next $T$ lines contains two integers $R$ and $B$ separated by a space ($1 \le R, B \le 10000$).

For each test case print the maximum area on its own line, rounded to three digits after the decimal point. Always print exactly three digits after the decimal point.