The following figure shows a frustrum of a cone. Of the following mensuration (geometrical) expressions, which describes (a) the total circumference of the flat circular faces, (b) the volume, and (c) the area of the curved surface?
(i) π(r1 + r2)[h2 + (r1 – r2)2]1/2
(ii) 2π(r1 + r2)
(iii) πh(r12 + r1r2 + r22).