[reefburnaby]

Hello,

Let's define some equations.
A = pi * R * R
D = 2 * R

so

A = pi * D * D / 4

where pi = 3.14159..., D = diameter, R is radius.

The area of the whole circle is

AW = pi * 2.5 * 2.5 / 4
AW = pi * 25/16 square inchs.

The area of the circle that is trimmed off is

AT = pi * 1.5 * 1.5 /4
AT = pi * 9/16 square inches

The remaining "donut" that is 1/2 thick and 2.5" diameter (outside) is

AD = AW - AT
AD = pi (25/16 - 9/16)
AD = pi square inches.

So...Darren is correct if it is a donut. On the other hand, if it is a 1/2" slot (basically a semicircle)...then this is not the correct solution. Hope that helps.

- Victor.