Page:Sheet Metal Drafting.djvu/181

Rh '''75. Related Mathematics on Short Handled Dipper.'—Volume of a Frustum of a Cone of Revolution.''—The frustum of a cone has a circular top and a circular base. These are known as the upper and lower bases of the frustum. The altitude of the frustum is the shortest distance between the upper and lower bases, and is always measured perpendicularly. The volume of a frustum is found by adding together the area of the upper base, the area of the lower base, and the square root of the product of the upper base area times the lower base area; the sum of these quantities is then multiplied by one-third of the altitude. Expressed as a formula in which

In applying this formula to Fig. 236, the areas of the upper and lower bases must first be computed.

Known values can now be substituted in this formula

Performing the arithmetic: