Legendre, A. M. (Adrien Marie), 1752-1833, Brewster, David, Sir, 1781-1868, Davies, Charles, 1798-1876 · New York, Wiley & Long · leaf 133
hey are parallel. ■\ A D\ p T^ \ \ \ B \ PROPOSITION X. THEOREM. If a plam cat two parallel planes, the lines of intersection will be parallel. Let the parallel planes NM,QP, be intersected by the planeEll ; then will the lines of inter-section EF, Gil, be parallel. For, if the lines EF, GH,… … HiOPOSITION XI. THEOREM. If two planes are parallel, a straij^ht line which is perpendicularto cue, is also perpendicular to the other. M À 134 GEOMETRY Let MN, PQ, be two parallelplanes, and let AB be perpendicular to NM ; then will it also be per-pendicular to QP. Having drawn any line BC inthe…
Trigonometry · Geometry
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