Page:An introduction to linear drawing.djvu/92

 ﻿When you have obtained two or three decimal fig- ures in the quotient, it is useless to carry the calcula- tion any further, as they will be too small.

We shall now endeavour to apply these principles.

SECTION I.

OF LINES.

Problem I. To find a side of a rectangular trian- gle, the two others being known.

Rule. Multiply by itself each of the known sides, then add them together if you wish to find the greater side ; and subtract the lesser number from the greater if you wish to find one of the lesser sides. Then you will have the same result as if you had multiplied the unknown side by itself. Of course, you have only to find what number, multiplied by itself, will give this result.

Example 1. The smaller sides of a rectangular tri- angle, (figs. 12 and 13, Classl.) are one 3, and the oth- er 4 inches, find the larger side.

3	times 3 are 9

4	times 4 are 16

These added make 25

5 multiplied by itself makes 25, and the greater side or side required, must be 5 inches.

Example 2. \n a rectangle, (1st Class, fig. 14,) it is known that the base is 8 inches, 54 hundredths, the