American text books of art education : Geometrical drawing (1873)
Smith, Walter, 1836-1886 · Boston : James R. Osgood & Co. · leaf 70
the vertical angle, multiply the number ofdegrees in one angle at the base by 2, and the. difference betweenthe product and ISO0 will equal the number of degrees in the verti-cal angle. Prob. 70. — On a given base A B, to construct a Irianule liavinaangles of 60°, 30°, and 90°. Draw a line A B. At…
Geometrical drawing
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