## Elements of Geometry |

### From inside the book

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**adjacent angles**BAC , BAD , are equal , each of these angles is called a right angle , and the line AB is said to be perpendicular to CD . 11. Every angle BAC ( fig . 4 ) , less than a right angle , is an acute angle ; and every angle ... 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 equiangular polygon is one which has all its**angles**equal . • 20. Two polygons are equilateral with respect to each other ... Page 4

... angles are equal . Demonstration . Let the straight line CD be perpendicular to Fig . 16. AB ( fig . 16 ) , and GH ...

... angles are equal . Demonstration . Let the straight line CD be perpendicular to Fig . 16. AB ( fig . 16 ) , and GH ...

**adjacent angles**ACD , BCD , which , taken together , are equal to two right angles . Demonstration . At the point C ... Page 5

... angles ACE , ECD ; therefore ACD + BCD is the sum of the three angles ACE , ECD , BCD . The first of these is a right angle , and the two others are together equal to a right angle ...

... angles ACE , ECD ; therefore ACD + BCD is the sum of the three angles ACE , ECD , BCD . The first of these is a right angle , and the two others are together equal to a right angle ...

**adjacent angles**Of Perpendicular and Oblique Lines . 5. Page 6

Adrien Marie Legendre. THEOREM . Fig . 2 33. If two

Adrien Marie Legendre. THEOREM . Fig . 2 33. If two

**adjacent angles**ACD , DCB ( fig . 20 ) , are together equal to two right angles , the two exterior sides AC , CB , are in the same straight line . Demonstration . For if CB is not the ...### 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