1. The cross-sectional perimeter of the chimney is constant, while the height and surface area are variable.

2. the perimeter l = 4.71/3 =1.57.s = l * h =1.57 * 9 =14.6438+03.

3.l = 2∏R = 2 * 3. 14 * R = 1.57→R = 0.25