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PROBLEM?. 



PROBLEM XX YP- 



ffo ihalc a?r; regulai- Polygjfi on a given Line A B. 



Draw A o and B o, male- 

 ^g the angles A and 15 

 eacli equul to half the angle 

 of the pulygpn. With the 

 centre o, and radius o A, 

 describe a circle. Then ap- 

 ply the line A B continually- 

 round the circumference the 

 proper number of times, 

 and it is done. 



Note. Tho. angle of any polygon, of which the angles 

 o A B and q B A are each one half, is found thus : divide 

 the whole 360 degrees by the number of sides, and the 

 quotient will be the angle at the centre o ; then subtract 

 that from 180 degrees, and the remainder will be the an- 

 gle of the polygon, and is double of o A B, or of o B A. 

 And thus you will find the following table, containing the 

 degrees in the angle c at the centre, and the angle of th& 

 polygon> for all the regular figures from 3 to 12 sides. 



luoniXM 



