DEFINITIOKS. 



3«9 



50. A semkircle is half the cir- 

 cle, or a segment cut off by a di- 

 ameter. 



\ 



51. A sector Is any part of a 

 circle, bounded by an arc, and 

 two radiij drawn to its extremi- 

 ties. 



52. A quadrant y or quarter of a 

 circle, is a sector, having a quar- 

 ter of the circumference for its 

 arc, and its two radii are perpen- 

 dicular to each other. 





53. The height y ox attitude ^ of a 

 figure is a perpendicular let fall 

 from an angle, or its vertex, to 

 the opposite side, called the base. 



54. In a right-angled triangle, the side opposite to the 

 riglit angle is called the hypotenuse ; and the other two 

 the legSy or sides y or sometimes the base and perpendicular. 



^5. When an angle is denoted by 

 three letters, of which one stands 

 at the angular point, and the other 

 two on the two_sides, that, which 

 stands at the angular point, is read 

 in the middle. 



