A treatise on special or elementary geometry (1877)
Olney, Edward, 1827-1887, Olney, Edward, 1827-1887. Elements of trigonometry, plane and spherical · New York : Sheldon · leaf 131
e of AC. Since angle BAC = angleACD, AB will take the directionCD, and B will fall in CD, or CDproduced. Since angle BCA =angle DAC, CB will take thedirection AD, and B will foil in AD, or in AD produced. There-fore, as Bfalls at the same time in AD and CD, it falls at the intersection D, andthe… … Fig. 1S2. 244. TJteoreni. oisect each other. PROPOSITION XII. The diagonals of a parallelogram mutually Dem.—Let AC and DB be the diagonals ofthe parallelogram ABCD («), and Q their inter-section ; then, DQ = QB, and AQ = QC. For, take the triangle AQB, and apply it to DQC, by placing BA in its…
Geometry · Trigonometry
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