If I remember my high school geometry correctly, I believe the area of a trapezoid with a height of 2" (the depth of the pan in your case) would be 3.14 x (ID + OD).
For those who don't have 2" pans, the general formula for the area of a trapeziod is 1/2 * (b1+b2) * h, where b1 and b2 are the lengths of the parallel sides, and h is the length of a line perpendicular to b1 and b2 that bisects both lines (fig. 1).
Pete-zza, I'm not sure how the depth of a nesting pan in measured since I don't own one, and I'm not sure it's all that significant, but just to be completely precise (or anal, depending on how you look at it
), in the case of a pizza pan where the length of the sloped side (h) is 2" (fig. 2), the formula does indeed reduce to 3.14 * (b1+b2). For a pan that is 2" tall from base to the rim (assuming a light gauge metal), however, h would be slightly greater than 2" since h is the distance across the sloped side, which would necessarily be > 2" since h would be the hypotenuse of a right triangle one of whose sides is 2" and the other, (od-id)/2 (fig. 3). For a 2" deep pan, id=15", od=17", h would be ~ 2 15/64" (h= √(22
) = √5), whereas a pan with a 15" id and a side length (h) of 2" would have od=16.78", or a difference of about 12 sq. in. which, for most purposes, isn't enough to worry about.