The American house-carpenter; a treatise upon architecture, cornices and mouldings, framing, doors, windows, and stairs. Together with the most important principles of practical geometry (1852)
Hatfield, R. G. (Robert Griffith), 1815-1879 · New York : J. Wiley · leaf 77
triangle amount toa right angle, the remaining angle is a right angle. 153.—Corollary. If any two angles of a triangle are togetherequal to the remaining angle, that remaining angle is a right,angle. 154.—Corollary. If any two angles of a triangle are eachequal to two-thirds of a right angle, the… … 156.—Proposition. If from the extremities of the diameter ofa semi-circle, two straight lines be drawn to any point in the cir-cumference, the angle formed by them at that point will be aright angle. Let a b c, (Fig. 107,) be a given semi-circle ; anda b and b c, lines drawn from the extremities of…
Carpentry · Architecture
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