## Elements of Geometry |

### From inside the book

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**plane**geometry , and four of solid geometry . The first section , entitled first principles , & c . contains the prop- erties of straight lines which meet those of perpendiculars , the theorem upon the sum of the**angles**of a triangle ... Page 1

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**plane**is a surface in which , any two points being taken , the straight line joining those points lies wholly in ...**Angles**, like other quantities , are susceptible of addition ELEMENTS OF GEOMETRY. ... Page 2

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**angle**, DEF , greater than a right**angle**, is an obtuse**angle**. 12. Two lines are said to be parallel ( fig . 5 ) , when , being situated in the same**plane**, and produced ever so far both ways , they do not meet . 13. A**plane**figure is a ... Page 3

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**angles**not adjacent , as AC ( fig . 42 ) . 19. An equilateral polygon is one which has all its sides equal ; an ...**PLANE**FIGURES . SECTION FIRST . Axioms . 3. Page 4

Adrien Marie Legendre. PART FIRST . OF

Adrien Marie Legendre. PART FIRST . OF

**PLANE**FIGURES . SECTION FIRST . First Principles , or the Properties of Perpendicular , Oblique , and Parallel Lines . THEOREM . 27. ALL right**angles**...**angle**EGH = HGF , it follows that Fig . 17 . But ...### Other editions - View all

### Common terms and phrases

ABC fig adjacent angles altitude angle ACB angle BAC 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 angles equiangular equilateral equivalent faces figure formed four right angles frustum GEOM given point gles greater hence homologous sides hypothenuse inclination intersection isosceles triangle JOHN CRERAR LIBRARY join less Let ABC let fall line AC mean proportional measure the half meet multiplied number of sides oblique lines opposite parallelogram parallelopiped perimeter perpendicular plane MN polyedron prism produced proposition radii radius ratio rectangle regular polygon right angles Scholium sector segment semicircle semicircumference side BC similar solid angle sphere spherical polygons spherical triangle square described straight line tangent THEOREM three angles triangle ABC triangular prism triangular pyramids vertex vertices whence