## Elements of Geometry |

### From inside the book

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**vertex**of the angle ; the lines AB , AC , are its sides . An angle is sometimes denoted simply by the letter at the ver- tex , as A ; sometimes by three letters , as BAC , or CAB , the letter at the**vertex**always occupying the middle ... Page 2

... ( fig . 14 ) , which has its sides equal without having its angles right angles ; The trapezoid ( fig . 15 ) , which has two only of its sides parallel . 18. A diagonal is a line which joins the

... ( fig . 14 ) , which has its sides equal without having its angles right angles ; The trapezoid ( fig . 15 ) , which has two only of its sides parallel . 18. A diagonal is a line which joins the

**vertices**2 Elements of Geometry . Page 3

Adrien Marie Legendre. 18. A diagonal is a line which joins the

Adrien Marie Legendre. 18. A diagonal is a line which joins the

**vertices**of two angles not adjacent , as AC ( fig . 42 ) . 19. An equilateral polygon is one which has all its sides equal ; an equiangular polygon is one which has all its ... Page 6

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**vertex**are equal . Demonstration . Since DE is a straight line , the sum of the angles ACD , ACE , is equal to two right angles ; and , since AB is a straight line , the sum of the angles ACE , BCE , is equal to two right angles ... Page 9

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**vertex**A to the point D the middle of the base BC ; the two triangles ABD , ADC , will have the three sides of the one , equal to the three sides of the other , each to each , namely , AD common to both , AB = AC , by hypothesis , and ...### Other editions - View all

### Common terms and phrases

ABC fig adjacent angles altitude angle ACB angle BAD base ABCD bisect centre chord circ circular sector circumference circumscribed common cone consequently construction convex surface Corollary cube cylinder Demonstration diagonals diameter draw drawn equal and parallel equiangular equilateral equivalent faces figure four right angles frustum Geom gles greater hence homologous sides hypothenuse inclination inscribed circle isosceles join less let fall line AC manner mean proportional measure the half meet multiplied number of sides oblique lines opposite parallelogram parallelopiped perimeter perpendicular plane MN polyedron prism proposition pyramid S-ABC quadrilateral radii radius ratio rectangle regular polygon right angles right-angled triangle Scholium segment semicircumference side BC similar solid angle sphere spherical polygons spherical triangle square described straight line tangent THEOREM three plane angles triangle ABC triangular prism triangular pyramids vertex vertices whence