## Elements of Geometry |

### From inside the book

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Page vi

... angles of a triangle , the theory of parallel lines , & c . The second section , entitled the circle , treats of the ...

... angles of a triangle , the theory of parallel lines , & c . The second section , entitled the circle , treats of the ...

**right**-**angled triangle**, those of equiangular triangles , of similar figures , & c . We shall be found fault vi ... Page 2

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**triangle**; that of four sides is called a quadrilateral ; that of five sides , a pentagon ; that of six , a hexa ...**right angles**; The trapezoid ( fig . 15 ) , which has two only of its sides parallel . 18. A diagonal is a line which ... Page 12

Adrien Marie Legendre. = 1. The

Adrien Marie Legendre. = 1. The

**triangle**BCF is equal to the**triangle**BCA ; for the**right angle**CBF = CBA , the side CB is common , and the side BF BA ; therefore the third side CF is equal to the third side AC ( 36 ) . But AF < AC + CF ... Page 13

Adrien Marie Legendre. THEOREM . 56. Two

Adrien Marie Legendre. THEOREM . 56. Two

**right**-**angled triangles**are equal , when the hypothenuse and a side of the ... triangle ABC will be equal to the**right**-**angled triangle**DEF . The proposition will evidently be true , if the third ... Page 18

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**triangle**being given , or only their sum , the third will be known by subtracting the sum of these angles from two**right angles**. 74. Corollary u . If two angles of one ...**right angles**, so that if a**right angle**be 18 Elements of Geometry .### 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