390 



t>pOMETRY. 



56. Th'j clrcuinfercncc of every circle is supposed to be 

 divided iato 360 equ«l parts, called degrees ; and each de- 

 gree iiiio 60 mh:::ieSf each minute into 60 seconds, and so 

 on. Hence ^ semicircle contain? 180 degrees, and a quad- 

 rant 90 degrees. 



« 



57. The measure of a right- 

 lined angle is an arc of any cir- ,• 

 cle, contained between the two / 

 lines, v/hich form that angle, the \ 

 angular point being the centre \ \ 

 and it is estimated by the num- 

 ber of degrees, contained in that 

 arc. Hence a Tight angle is an angle, of 90 degrees. 



58. Identical fgures 7XXQ. snc\ as have all the sides and 

 all the angles of one respectively equal to all the sides and 

 ail the angles of the other, each to each ; so that, if one 

 figure were applied to, or laid upon, the other, ail the 

 sides of it would exactly fail upon and cover all the sides 

 of the other 5 the tv.ro becoming coincident. 



59. An angle in a segment is that, which is 

 contained by two lines, drawn .from any 

 point in the arc of the^ segment to the ex- 

 tremities of the arc. 



60. A right-lined figure is inscribed in a 

 cf'cley or ^e circle circutnscribes it, when all 

 the angular points of the figure are in the 

 circumference of the circle. 



61. A right-lined figure c'lrcnmscrihes a cir- 

 cloy or the circle is inscribed in it, when all the 

 sides of the figure* touch the circumference 

 ©f the circle. 



62. 0ns 



