## Elements of Geometry |

### From inside the book

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Page vi

... , entitled the proportions of figures , contains the measure of surfaces , their comparison , the properties of a

... , entitled the proportions of figures , contains the measure of surfaces , their comparison , the properties of a

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

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...

**right angle**, and the line AB is said to be perpendicular to CD . 11. Every ...**triangle**; that of four sides is called a quadrilateral ; that of five sides ... angled**triangle**is that which has one**right angle**. The side ... 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 ... Page 18

... angle DEH would have its sides parallel to those of the angle BAC , but the two angles would not be equal . In this case the angle DEH and the angle BAC would together make two

... angle DEH would have its sides parallel to those of the angle BAC , but the two angles would not be equal . In this case the angle DEH and the angle BAC would together make two

**right angles**. THEOREM . 72. In every**triangle**the sum of the ...### 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