## Elements of Geometry and Trigonometry |

### From inside the book

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Page 47

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**ABCD**be a parallelogram : then will AB be equal to DC , and AD to BC . For , draw the diagonal BD . Then , because AB and DC are parallel , the A angle DBA is equal to its alternate D angle BDC ( P. XX . , C. 2 ) : and , because AD and ... Page 48

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**ABCD**, let AB be equal to DC , and AD to BC : then will it be a parallelogram . Draw the diagonal DB . Then , the triangles ADB and CBD , will have A D the sides of the one equal to the sides of the other , each to each and therefore ... Page 49

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**ABCD**be a parallelogram , and B AC , BD , its diagonals : then will AE be equal to EC , and BE to ED . For , the triangles BEC and AED , have the angles EBC and ADE equal A E D ( P. XX . , C. 2 ) , the angles ECB and DAE equal , and the ... Page 53

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**A B C D**; whence , : :: : C Multiplying both members by B ' we have , C Ꭰ A B ; or , A C B D ; : which was to be proved . PROPOSITION IV . THEOREM . If one couplet in each of two proportions is the same , the other couplets will form a ... Page 79

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**ABCD**, are together equal to two right angles ; for the angle DAB is measured by half the arc DCB , the angle DCB by half the arc A D B DAB hence , the two angles , taken together , are mea- sured by half the circumference : hence ...### Other editions - View all

Elements of Geometry and Trigonometry: From the Works of A. M. Legendre Adrien Marie Legendre,Charles Davies No preview available - 2016 |

### Common terms and phrases

ABē ABCD ACē adjacent angles altitude angle ACB apothem Applying logarithms base and altitude centre chord circle circumference circumscribed coincide cone consequently convex surface corresponding cosec Cosine Cotang cylinder denote diameter distance divided draw drawn edges equally distant feet find the area Formula frustum given angle given line greater hence homologous hypothenuse included angle interior angles intersection less Let ABC log sin logarithm lower base mantissa mean proportional measured by half number of sides opposite parallel parallelogram parallelopipedon perimeter perpendicular plane MN polyedral angle polyedron prism PROPOSITION proved pyramid quadrant radii radius rectangle regular polygon right-angled triangle Scholium secant segment semi-circumference side BC similar Sine slant height sphere spherical angle spherical polygon spherical triangle square straight line Tang tangent THEOREM triangle ABC triangular prisms upper base vertex vertices whence

### Popular passages

Page 28 - If two triangles have two sides of the one equal to two sides of the...

Page 100 - The area of a triangle is equal to half the product of its base by its altitude.

Page 99 - The area of a parallelogram is equal to the product of its base and its height: A = bx h.

Page 59 - A chord is a straight line joining the extremities of an arc.

Page 124 - If two polygons are composed of the same number of triangles, similar each to each and similarly placed, the polygons are similar.

Page 214 - A sphere is a solid bounded by a curved surface, every point of which is equally distant from a point within called the center.

Page 43 - C' (89) (90) (91) (92) (93) 112. In any plane triangle, the sum of any two sides is to their difference as the tangent of half the sum of the opposite angles is to the tangent of half their difference.

Page 52 - If the product of two quantities is equal to the product of two other quantities, two of them may be made the extremes, and the other two the means of a proportion.

Page 123 - Similar triangles are to each other as the squares of their homologous sides.

Page 182 - The upper end of the frustum of a pyramid or cone is called the upper base...