| 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 - Geometry - 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
...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 - 400 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
...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 - 864 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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