Books Books 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. Elements of Geometry: With Practical Applications to Mensuration - Page 170
by Benjamin Greenleaf - 1868 - 320 pages ## The Harpur Euclid: An Edition of Euclid's Elements

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... ## The Elements of Plane and Solid Geometry ...

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... ## Examinations Papers

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... ## Plane and Solid Geometry

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.... ## Year Book ... with Announcements

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... ## Plane and Solid Geometry

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 Examination Papers

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.... ## The Elements of Euclid: Viz. the First Six Books, Together with the Eleventh ...

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... ## A Text-book of Geometry

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... 