## Elements of Geometry and Trigonometry |

### From inside the book

Page 10

...

...

**quadrilateral**; that of five , a pentagon ; that of six , a hexagon ; that of seven , a heptagon ; that of eight , an octagon ; that of nine , a nonagon ; that of ten , a decagon ; and that of twelve , a dodecagon . C 15. An equilateral ... Page 11

...

...

**quadrilaterals**, we distinguish : The square , which has its sides equal , and its an- gles right - angles . The rectangle , which has its angles right an- gles , without having its sides equal . The parallelogram , or rhomboid , which ... Page 30

... in the number of sides diminished by two . Cor . 1. The sum of the angles in a

... in the number of sides diminished by two . Cor . 1. The sum of the angles in a

**quadrilateral**is equal to two right angles multiplied by 4-2 , which amounts to four right angles : hence , if all the angles of 30 GEOMETRY . Page 31

...

...

**quadrilateral**are equal , each of them will be a right angle ; a conclusion which sanctions the seventeenth Definition , whère the four angles of a**quadrilateral**are asserted to be right angles , in the case of the rectangle and the ... Page 32

...

...

**quadrilateral**are equal , each to each , the equal sides will be parallel , and the figure will be a par- allelogram . Let ABCD be a**quadrilateral**, having its opposite sides respectively equal , viz . AB DC , and AD = BC ; then will ...### Other editions - View all

### Common terms and phrases

adjacent adjacent angles altitude angle ACB angle BAC ar.-comp base multiplied bisect Book centre chord circ circumference circumscribed common cone consequently convex surface cylinder diagonal diameter dicular distance draw drawn equal angles equally distant equation equiangular equivalent figure formed four right angles frustum given angle given line gles greater homologous sides hypothenuse inscribed circle inscribed polygon intersection less Let ABC let fall logarithm measured by half number of sides opposite parallelogram parallelopipedon pendicular perimeter perpen perpendicular plane MN polyedron polygon ABCDE prism proportional PROPOSITION pyramid quadrant quadrilateral quantities radii radius ratio rectangle regular polygon right angled triangle S-ABC Scholium secant secant line segment side BC similar solid angle solid described sphere spherical polygon spherical triangle square described straight line tang tangent THEOREM triangle ABC triangular prism vertex