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 rightangle. 154.—Corollary. If any two angles of a triangle are eachequal to two-thirds of a right angle, the… … \m.~-Proposition. If from the extremities of the diameter ofa semi-circle, two straight hues be drawn to any point in the cir-cumference, the angle formed by them at that point will be aright angle. Let a h c, [Fig. 107,) be a given semi-circle ; anda 6 and 6 c, lines drawn from the extremities of…
Carpentry · Architecture
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