# Pi square?

1. Oct 24, 2004

### arivero

Is there any geometric figure whose calculation (area, perimeter, ...) involves the terms pi^2 or (pi^2-1) ?

2. Oct 24, 2004

### HallsofIvy

Staff Emeritus
I thought it was pretty well known that the area of a circle of radius r is
$$\pi r^2$$?

3. Oct 24, 2004

### arildno

Sure, check up the torus..
The surface area of a torus with big radius R and small radius r has surface area:
$$A=4\pi^{2}Rr (r<R)$$

4. Oct 24, 2004