## Elements of Geometry and Trigonometry |

### From inside the book

Results 1-5 of 24

Page 10

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**Angles**, like all other quantities , are susceptible of addition ...**right**angle ; and the line AB is said to be perpendicular to CD . 11. Every ...**four**sides , a quadrilateral ; that of five , a pentagon ; that of six , a hexagon ; that ... Page 16

... four angles formed about a point by two straight lines , which intersect each other , are together equal to

... four angles formed about a point by two straight lines , which intersect each other , are together equal to

**four right angles**: for the sum of the two angles ACE , ECB , is equal to two right angles ; and the sum of the other two , ACD ... Page 27

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**right angles**. In the same manner it may be proved that OGA + GOC is equal to two**right angles**. Cor . 1. If OGB is ...**four**acute angles are equal to each other , and so also are the**four**obtuse angles . PROPOSITION XXI . THEOREM . If a ... Page 30

... angles of another , the third angles will also be equal , and the two triangles will be mutually equiangular . Cor . 3. In any triangle there can be but one right angle ; for ...

... angles of another , the third angles will also be equal , and the two triangles will be mutually equiangular . Cor . 3. In any triangle there can be but one right angle ; for ...

**four right angles**: hence , if all the angles of 30 GEOMETRY . Page 31

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**four**angles of a quadrilateral are asserted to be**right angles**, in the case of the rectangle and the square . Cor . 2. The sum of the angles of a pentagon is equal to two ... right angles , is equal to twice as many**right angles**BOOK I. 31.### Other editions - View all

### Common terms and phrases

adjacent adjacent angles altitude angle ACB angle BAC ar.-comp base multiplied bisect Book centre chord circ circumference circumscribed common cone convex surface Cosine Cotang cylinder diagonal diameter dicular distance draw drawn equal angles equally distant equiangular equivalent figure formed four right angles frustum given angle given line gles greater homologous sides hypothenuse inscribed polygon intersection less Let ABC let fall logarithm measured by half number of sides oblique lines opposite parallelogram parallelopipedon pendicular perimeter perpen perpendicular plane MN polyedron polygon ABCDE prism proportional PROPOSITION pyramid quadrant quadrilateral quantities radii radius ratio rectangle regular polygon right angled triangle S-ABC Scholium secant secant line segment side BC similar sine solid angle solid described sphere spherical polygon spherical triangle square described straight line tang tangent THEOREM triangle ABC triangular prism vertex