## An Elementary Geometry |

### From inside the book

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**ABCD**be a parallelogram ; then will A B D C , B C = AD , the angle AC , and B = D. Draw the diagonal BD . As BC and A B C AD are parallel , the alternate angles CBD and BDA are equal ( 17 ) ; and as AB and DC are parallel , the ... Page 19

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**ABCD**; then B E G C 1st . EF is parallel to BC and AD . Through F draw G H parallel to B A , meeting AD produced in H. The an- gles GFC and DFH are equal ( 11 ) ; also the angles G C F and FDH ( 17 ) ; and the side CF is equal to FD ... Page 30

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**abcd**= e : f ab = ab = = ( A ) ad bc ( B ) af be ( C ) Adding ( A ) , ( B ) , ( C ) a ( b + d + f ) = b ( a + c + e ) Hence , by ( 14 ) a : b = a + c + e : b + d + f THEOREM X. 24. If there are two sets of quantities in proportion ... Page 32

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**ABCD**be a rectangle ; its area ADXA B. BO P Q R C G N F M S E L A H I J K D Suppose AB and AD to be divided into any number of equal parts , AE , EF , AH , HI , & c . , and through the points of division , lines E L , FM , HO , IP , & c ... Page 33

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**ABCD**; then the area of**ABCD**ADX DF . = A F C D At A draw the perpendicular A E meet- ing CB produced in E ; A EFD is a rectangle equivalent to the parallelogram ABC D. For the two triangles A E B and DFC , having the sides AE , AB ...### Other editions - View all

### Common terms and phrases

A B C A B D ABCD adjacent adjacent angles altitude angle ABC apothem base and altitude centre chord circ circumference cone construct the triangle convex surface Corollary cylinder diagonals diameter distance divided dodecagon equal altitudes equally distant equilateral feet frustum given angle given circle given line given point given side half the arc hexagon homologous sides hypothenuse included angle infinite number inscribed internal angles intersection isosceles triangle Let ABCDEF line joining lines A B measured by half mutually equiangular number of sides opposite sides parallelogram parallelopiped perimeter perpendicular plane parallel quadrilateral radii radius ratio rectangle regular polygon respectively equal rhombus right angles right prism right pyramid right triangle Scholium secant segment similar triangles slant height sphere tangent THEOREM VII trapezoid triangle ABC triangles are equal vertex