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 73
143.—Proposition, A diagonal crossing a parallelogram di-vides it into two equal triangles. Let abed, (Fig. 101,) be agiven parallelogram, and b c, a line crossing it diagonally. Then,as a c is equal to b d, and a b to c d, the angle at a to the angleat c?, the triangle, J, must, according to Art.… … 144.—Proposition. Let a. b c d, (Fig. 102,) be a given pa-rallelogram, and b c a diagonal. At any distance between a b andc d, draw e/, parallel to a b ; through the point, g, the intersectionof the lines, b c and e/, draw h i, parallel to b d. In every paral-lelogram thus divided, the…
Carpentry · Architecture
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