## An Elementary Geometry |

### From inside the book

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**dodecagon**? 21. If the parallel sides of a trapezoid are respectively 8 feet and 13 feet in length , how long is the line joining the middle points of the other two sides ? 22. If one of the angles of a parallelogram is 120 ° , how many ... Page 24

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**dodecagons**. 4th . Squares and octagons . How many of each must there be at each angular point ? 97. If three kinds of regular figures , with sides of the same length , are to be used at each angular point , show that the pavement can ...### 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