# A Rudimentary Treatise on Masonry and Stonecutting. [With] Plates

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## Description

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1849 edition. Excerpt: ...an angle by this means it is, therefore, necessary that the scale should be divided decimally, and that the radius chosen should be ten, or some multiple of that number. Instead of doubling the sine, we may use half the radius, which is a much simpler plan, although the principle is not so immediately apparent. Example.--To set off an angle of 70, the sides to be not less than 8 ft. long. Look in the table for the natural sine of 35, which is "5735764. The length of the chord will be twice this, or 1,1471528. Taking the radius in inches, the nearest convenient number will be 100, and accordingly the decimal point must be shifted two places, making the length of the chord 114-71528 inches. It is always desirable in plotting angles, that the points found should be beyond the work, and not within it, so that there may be no necessity for producing their sides. 81. An Obtuse Angle is plotted by producing one of the sides and setting off the supplement of the required angle. 82. Measurement of right-angled Triangles.--In any right-angled triangle, if one side, and one of the acute angles be given, the remaining sides can be readily found by calculation, with the help of a table of sines, cosines, secants, and tangents. We presume the reader to be familiar with the method of doing this, but it may be useful here to insert the formulae. In the right-angled triangle abc, fig. 19, plate 1. Let /. ab c be the given angle--the Lbac will of course be its complement. 1 st, Let the hypothenuse a J be the given side, then side ac = ab x sine L abc and side bc--ab x cos L abc. 2nd, Let the given side be one of those containing the right angle, as b c. then side ab--be x sec / abc and side ac--be x tang L abc. If any two sides are given, the third side may...show more

## Product details

• Paperback | 38 pages
• 189 x 246 x 2mm | 86g
• Miami Fl, United States
• English
• black & white illustrations
• 1236639340
• 9781236639349