An Elementary Geometry |
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Page 9
... . B A C E 27. An Isosceles Triangle is one which has two of its sides equal ; as DEF . 28. An Equilateral Triangle is one whose sides are all equal ; as IGH . D F G I H 29. A Right Triangle is one which has a right 1 * BOOK I. 9.
... . B A C E 27. An Isosceles Triangle is one which has two of its sides equal ; as DEF . 28. An Equilateral Triangle is one whose sides are all equal ; as IGH . D F G I H 29. A Right Triangle is one which has a right 1 * BOOK I. 9.
Page 10
... isosceles triangle , as DEF , in which DE = EF , the third side DF is always considered the base . THEOREM VII . 33. The sum of the angles of a triangle is equal to two right angles . Let ABC be a triangle ; the sum of its three angles ...
... isosceles triangle , as DEF , in which DE = EF , the third side DF is always considered the base . THEOREM VII . 33. The sum of the angles of a triangle is equal to two right angles . Let ABC be a triangle ; the sum of its three angles ...
Page 12
... triangles coincide , and are equal in all respects . THEOREM X. 42. In an isosceles triangle the angles opposite the equal sides are equal . In the isosceles triangle ABC let B AB and BC be the equal sides ; then the angle A is equal to ...
... triangles coincide , and are equal in all respects . THEOREM X. 42. In an isosceles triangle the angles opposite the equal sides are equal . In the isosceles triangle ABC let B AB and BC be the equal sides ; then the angle A is equal to ...
Page 13
... isosceles triangle bisects the triangle . And , conversely , the perpendicular bisecting the base of an isos- celes triangle bisects the angle opposite , and also the triangle . 44. Cor . 2. An equilateral triangle is equiangular ...
... isosceles triangle bisects the triangle . And , conversely , the perpendicular bisecting the base of an isos- celes triangle bisects the angle opposite , and also the triangle . 44. Cor . 2. An equilateral triangle is equiangular ...
Page 14
... isosceles triangle ; and the angle ABD = ADB ( 42 ) ; also , since BC = CD , BCD is an isosceles triangle ; and the angle DBC = CDB ; there- fore the whole angle ABC = ADC ; therefore the triangles ABC and ADC , having two sides and the ...
... isosceles triangle ; and the angle ABD = ADB ( 42 ) ; also , since BC = CD , BCD is an isosceles triangle ; and the angle DBC = CDB ; there- fore the whole angle ABC = ADC ; therefore the triangles ABC and ADC , having two sides and the ...
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Common terms and phrases
ABC and DEF ABCD adjacent altitude angle ABC apothem base and altitude bisect centre chord circ circumference coincide cone construct the triangle convex surface Corollary cube cylinder diameter distance divided dodecagon EATON'S equal altitudes equally distant equiangular equilateral feet frustum given angle given circle given line given point given side given square given triangle half the arc hexagon homologous sides hypothenuse included angle infinite number inscribed internal angles intersection isosceles triangle Let ABCDEF line joining mean proportional measured by half number of sides opposite sides parallel planes parallelogram parallelopiped perimeter perpendicular plane parallel propositions quadrilateral radii radius ratio rectangle regular polygon respectively equal rhombus right angles right prism right pyramid right triangle Scholium secant segment similar triangles slant height sphere tangent THEOREM VIII trapezoid triangle ABC vertex
Popular passages
Page 25 - Four quantities are in proportion when the ratio of the first to the second is equal to the ratio of the third to the fourth.
Page 30 - If any number of quantities are proportional, any antecedent is to its consequent as the sum of all the antecedents is to the sum of all the consequents. Let a : b = c : d = e :f Now ab = ab (1) and by Theorem I.
Page 27 - If the product of two quantities is equal to the product of two others, the...
Page 43 - The area of a regular polygon is equal to half the product of its perimeter and apothem.
Page 11 - If two triangles have two sides, and the included angle of the one equal to two sides and the included angle of the other, each to each, the two triangles are equal in all respects.
Page 23 - If two triangles have two sides of one respectively equal to two sides of the other, but the third sides unequal...
Page 20 - ... polygon, is equal to twice as many right angles as the polygon has sides minus two.
Page 49 - A Circle is a plane figure bounded by a curved line every point of which is equally distant from a point within called the center.
Page 70 - A right cylinder is a solid described by the revolution of a rectangle about one of its sides.
Page 64 - DEFINITIONS. 1 . A straight line is perpendicular to a plane, when it is perpendicular to every straight line of the plane which it meets.