If two intersecting planes are each perpendicular to a third plane, their intersection is perpendicular to that plane. Solid Geometry - Page 362by William Betz, Harrison Emmett Webb - 1916 - 178 pagesFull view - About this book
| College Entrance Examination Board - Mathematics - 1920 - 108 pages
...hours [The question paper Mathematics CD, Plane and Solid Geometry, is printed on page 1. ] 1. Prove: If two intersecting planes are each perpendicular to a third plane, their intersection is also perpendicular to that plane. 2. Prove: The angle formed by two arcs of great circles is measured... | |
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