12/1 / 4/5=
12/1 * 5/4 =
60/4 = 15
they can make 15 bowls
Under the given transformation, the Jacobian and its determinant are
so that
where is the region transformed into the - plane. The remaining integral is the twice the area of .
Now, the integral over is
but through the given transformation, the boundary of is the set of equations,
We require that , and the last equation tells us that we would also need . This means and , so that the integral over is