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 75
the parallelo-gram will be equal to double the triangle. Thus, the paral-lelogram, a dj {Fig. 103,) is double, {Art. 143,) the triangle,c e d. 147.—Proposition. Let a h c d, {Fig. 104,) be a given quad-rangle with the diagonal, a d. From h, draw b e, parallel to a d;extend cdto e ; join a and e ;… … Fig. 104. lels, a d and h e, they are therefore equal, {^Art. 145, 146 ;) andsince the triangle, C, is common to both, the remaining triangles, Aand 5, are therefore equal; then B being equal to yl, the triangle,a e c, is equal to the quadrangle, a h c d.
Carpentry · Architecture
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