| Robert Potts - Geometry - 1876 - 446 pages
...and AFis perpendicular to DE; therefore AFis perpendicular to each of the straight lines GH, DE. But if a straight line stand at right angles to each of two straight lines in the point of their intersection, it is also at right angles to the plane passing through them :... | |
| 1876 - 646 pages
...figures having the same area what one has the least perimeter? 5. 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. 6. A triangular pyramid is one-third of a triangular... | |
| Elias Loomis - Conic sections - 1877 - 458 pages
...common section. Hence, if two planes, etc. PROPOSITION IV. THEOREM. If a straight line be perpendicular to each of two straight lines at their point of intersection, it will be perpendicular to the plane in which these lines are. Let the straight line AB be perpendicular to... | |
| J. B. Millar - Geometry, Descriptive - 1878 - 264 pages
...another, their common section is a straight line 2 Theorem III. If a straight line be perpendicular to each of two straight lines at their point of intersection, it shall also be perpendicular to their plane 3 Theorem IV. Every plane which contains the normal to another... | |
| Isaac Sharpless - Geometry - 1879 - 282 pages
...the plane BC; it is therefore their common section. Proposition 4. Theorem.—If a straight line be at right angles to each of two straight lines at their point of intersection, it is at right angles to the plane in which these straight lines are. Let AB be at right angles to each... | |
| James Hamblin Smith - Euclid's Elements - 1879 - 378 pages
...0, ED Note. — The Propositions which follow are numbered as in iluolid. PROPOSITION IV. THEOREM. If a straight line stand at right angles to each of two i lines, at the point of their intersection, it must also be at right angles to the plane that passes... | |
| Oxford univ, local exams - 1880 - 394 pages
...figure inscribed in a circle is equal to the sum of the rectangles contained by its opposite sides. 12. If a straight line stand at right angles to each of...straight lines at their point of intersection, it shall also be at right angles to the plane which passes through them, that is, to the plane in which... | |
| Isaac Todhunter - Euclid's Elements - 1880 - 426 pages
...planes AB and BC cannot but be a straight line. Wherefore, if two planes &c. QED PROPOSITION 4. THEOREM. If a straight line stand at right angles to each of two straight lines at the point of their intersection, it shall also be at right angles to the plane which passes through... | |
| Woolwich roy. military acad, Walter Ferrier Austin - 1880 - 190 pages
...sides, find the area of the polygon, and hence prove that Trr2 is the area of a circle of radius r. 1. If a straight line stand at right angles to each of two straight lines at the point of their intersection, it shall be at right angles to the plane which passes through them.... | |
| Cornell University - 1880 - 868 pages
...triedral angles, a segment of a sphere, the axis of a parabola. 2. If a straight line be perpendicular to each of two straight lines at their point of intersection, it is perpendicular to the plane of those lines. 3. Two prisms are equal, if three faces including a triedral... | |
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