 | Baltimore (Md.). Department of Education - Mathematics - 1924 - 182 pages
...meet, they intersect in a straight line. 2 . If a line is perpendicular to each of two intersecting lines at their point of intersection, it is perpendicular to the plane of the two lines. 3 . Every perpendicular to a given line at a given point lies in a plane perpendicular... | |
 | National Committee on Mathematical Requirements - Mathematics - 1927 - 208 pages
...they intersect in a straight line, [1, cd] 2. If a line is perpendicular to each of two intersecting lines at their point of intersection it is perpendicular to the plane of the two lines. [2*, cd*] 3. Every perpendicular to a given line at a given point lies in a plane... | |
 | Pauline Sperry - Spherical trigonometry - 1928 - 88 pages
...every line lying in the plane and passing through its foot. Theorem. // a line is perpendicular to two lines at their point of intersection, it is perpendicular to the plane of the two lines. 2. Parallel planes. Definition. Two planes are parallel if they never meet. Theorem... | |
 | Geometry, Solid - 1930 - 18 pages
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If a straight line is perpendicular to each of two straight lines at their point of intersection, it is perpendicular to the plane of those lines. 
