DEFINITIONS. 



Heptagon. Octagon. 



587 



Nonagon, 



V. 



Undecagoiu. 



Decagon. 



Dodecagon. 



44. A circle is a plane figure 

 bounded by a curve line, called the 

 circumference .^ which is every w^here 

 equidistant from a certain point 

 within, called the centre. 



Note. The circumference itself 

 is often called a circle. 



45. The 



