| Edward Mann Langley, W. Seys Phillips - 1890 - 538 pages
...angles to all straight lines meeting it in that plane. PROP. 4.— If a straight line is at right angles **to each of two straight lines at their point of intersection, it is** at right angles to the plane in which they are. Let the st. line EF be xr to each of the two st. lines... | |
| Edward Albert Bowser - Geometry - 1890 - 418 pages
...perpendicular. Proposition 3. Theorem. 500. If a nfrnight line is perpendicular to each of two ytraight **lines at their point of intersection, it is perpendicular to the plane** of those lines. Hyp. Let OP bcJ_to PA, PB at the pt. P. To prove OP is J_ to the plane MN of these... | |
| 1891 - 644 pages
...first set as the first to the last of the other. If A : B=P : <?then A + B : A~ B — P + Q : P~ Q. 2. **If a straight line is perpendicular to each of two...their point of intersection, it is perpendicular to** their plane. The locus of a point equidistant from three straight lines which meet in a point, but... | |
| Seth Thayer Stewart - Geometry, Modern - 1891 - 422 pages
...plane at the greater distance is the longer line. PROP. II. If a straight line is perpendicular to **two straight lines at their point of intersection, it is perpendicular to the plane** of those lines. PROP. III. If two straight lines are perpendicular to the same plane, they are parallel.... | |
| Mining schools and education - 1891 - 862 pages
...of a circle to its diameter. SOLID AND SPHERICAL GEOMETRY. Demostrate the following propositions: 1. **If a straight line is perpendicular to each of two straight lines at their** intersection, it is perpendicular to their plane. 2. If two triedral angles have the three face angles... | |
| Seth Thayer Stewart - Geometry - 1891 - 428 pages
...at H in this last plane. PROPOSITION II. 43O. Theorem : // a straight lint- is perpendicular to tivo **straight lines at their point of intersection, it is perpendicular to the plane** of those lines. Statement: Let AB be perpendicular to CK and EF at B. Prove that / 2 is perpendicular... | |
| Yale University - 1892 - 200 pages
...other in what ratio? Of all plane figures having the same area what one has the least perimeter ? 5. **If a straight line is perpendicular to each of two...of intersection, it is perpendicular to the plane** of those lines. 6. A triangular pyramid is one-third of a triangular prism of the same base and altitude.... | |
| Euclid - Geometry - 1892 - 460 pages
...the plane of AB, AC ; .'. DA is perp. to this plane. QED PROPOSITION 4. THEOREM. [Euclid's Proof.] **If a straight line is perpendicular to each of two straight lines at their point of intersection, it** shall also be perpendicular to the plane in which they lie. Let the st. line EF be perp. to each of... | |
| George Albert Wentworth - Geometry - 1888 - 464 pages
...AND PLANES. PROPOSITION II. THEOREM. 472. If a straight line is perpendicular to each of two otJier **straight lines at their point of intersection, it is perpendicular to the plane** of the two lines. A Let AB be perpendicular to BC and BD at B. To prove AB perpendicular to the plane... | |
| Examinations - 1893 - 392 pages
...angle of a diedral angle, tangent plane, surface vf revolution, oblique prism, sphere. 15 2 Prove that **if a straight line is perpendicular to each of two...of intersection, it is perpendicular to the plane** of the two lines. 1 8 3 Prove that the sum of the face angles of any convex polyedral angle is less... | |
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