Let’s call, more conventional, the small and big radius r and R, where R>=r. Then the volume and area are:

```
V== 2 Pi^2 r^2 R
A== 2 Pi^2 r R
```

You specify V= 90 Pi^2. Then A can be written as a function of only one variable, e.g. r:

```
A = =V/r
R == V/(2 Pi^2 r^2)
```

Therefore, the largest value of A of infinity is reached for r->0.

The smallest value of A is reached if r == R:

```
rmin = V^(1/3)/(2^(1/3) (Pi)^(2/3))
```

In your case for V= 90 Pi^2