Page:An introduction to linear drawing.djvu/105

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2. The base of a pyramid is a pentagon of equal sides, (2d Class, fig. 12.) each side being 14 inches. The height is 22 inches. What are its solid contents ?

3. The base of a, pyramid is a right angled triangle, (1st Class, fig. 9.) of which the base, or longest side, is 13 inches, the shortest 6. The height of the pyramid is 19 inches. Required the solid consents.

Find the superficies of the base by Prob. I, Sect. I.

Problem IV. To find the volume or solid contents cf a truncated cone of parallel bases.

Note. A truncated cone is one whose topis cut off.

Rule. Multiply the radius of each base by itself, and multiply them together. Add together the three products. Multiply the whole sum by the height, and add to this product a third of a ninth of it, (that is, a 27th.)

Example 1. A Bucket is 14,5 inches in diameter at top, ana ii ,2 at bottom. Its perpendicular height is 17,5 inches. Required its solid contents.

14,5 multiplied by 14,5 gives . . . . * . . . 210,25

11,2 multiplied by 11,2 gives....... . 125,44

14,5 multiplied by 11,2 gives ......... 162,40

498,09

498 multiplied by the height 17,5 gives ... 8715 A ninth of which is ...... . 968,3

And a third of the ninth is....... 322,7

Cubick inches, 9037,7

2. How many such buckets of water would it take to filLthe caldron mentioned in Example 3, Prob. I. of this^ect. ?

END.