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A STRAIGHT line is perpendicular to a plane, when it is perpendicular to every straight line which it meets in that plane.
A Course of Mathematics: In Two Volumes. For the Use of Academies, as Well ... - Page 306
by Charles Hutton - 1818

## Elementary Geometry: With Applications in Mensuration

Charles Davies - Geometry - 1850 - 218 pages
...three to 120°x3r=360°0 GEOMETRY. BOOK V. OF PLANES AND THEIR ANGLES* DEFINITIONS. 1 . A straight line is perpendicular to a plane, when it is perpendicular to every straight line of the plane which it meets. The point at which the perpendicular meets the plane, is...

## Elements of Geometry and Trigonometry: With Applications in Mensuration

Charles Davies - Geometry - 1886 - 334 pages
...the three to 120° X 3= 360" GEOMETRY. BOOK V. OF PLANES AND THE1B ANGLES. DEF1N1T1ONS. 1. A straight line is perpendicular to a plane, when it is perpendicular to every straight line of the plane which it meets. The point at which the perpendicular meets the plane, is...

## Elements of Geometry and Trigonometry from the Works of A.M. Legendre ...

Charles Davies - Geometry - 1854 - 436 pages
...always be placed as in the f1gure. BOOK VI. PLANES AND POLYEDRAL ANGLES. DEFINITIONS. 1. A straight line is perpendicular to a plane, when it is perpendicular to every straight line of the plane which passes through its foot : conversely, the plane is perpendicular to...

## Mathematical Dictionary and Cyclopedia of Mathematical Science: Comprising ...

Charles Davies, William Guy Peck - Mathematics - 1855 - 630 pages
...tangent to the curve at the point of contact. Such a line is generally called a normal. Л straight line is perpendicular to a plane when it is perpendicular to every straight line drawn through its foot in that plane. A straight line is perpendicular to a curved surface...

## Elements of Geometry and Conic Sections

Elias Loomis - Conic sections - 1858 - 252 pages
...signifies circumference. SOLID GEOMETRY, BOOK VII. PLANES AND SOLID ANGLES Definitions. 1. A STRAIGHT line is perpendicular to a plane, when it is perpendicular to every straight line which it meets in that plane. Conversely, the plane in this case is per pendicular to...

## Plane and Solid Geometry: To which is Added Plane and Spherical Trigonometry ...

George Roberts Perkins - Geometry - 1860 - 468 pages
...obvious, from our definition of a plane (BI, D. XVII.), that this intersection is a straight line. II. A line is perpendicular to a plane, when it is perpendicular to all the lines in that plane which meet it. III. One plane is perpendicular to another, when every line...

## Elements of Plane and Spherical Trigonometry: With Practical Applications

Benjamin Greenleaf - Geometry - 1861 - 628 pages
...English mathematician. OOK VII. PLANES. — DIEDRAL AND TOLTEDRAL ANGLES. DEFINITIONS. 888. A STRAIGHT line is perpendicular to a plane, when it is perpendicular to every straight line which it meets in that plane. Conversely, the plane, in the same case, is perpendicular...

## Elements of Geometry and Trigonometry: With Practical Applications

Benjamin Greenleaf - Geometry - 1862 - 520 pages
...English mathematician. BOOK VII. PLANES. — DIEDRAL AND P0LYEDRAL ANGLES. DEFINITIONS. 388. A STRAIGHT line is perpendicular to a plane, when it is perpendicular to every straight line which it meets in that plane. Conversely, the plane, in the same case, is perpendicular...