tJEFINITKJNS. 



3S3 



13. All angle is the IncUnation, 

 or opening, of two lines, having 

 dilFerent directions, and meeting in 

 a point. 



14. Angles are right or oblique, acute or obtuse. 



15. A right angle is that, which is 

 made by one line perpendicular to an- 

 other. Or when the angles on each 

 side are equal to. one another, they 

 are right angles. 



1 6. An olllqtie angle is that, which 

 is made by two oblique lines, and 

 is either less or greater than a right 

 angle. 



1 7. An acute tingle is less than a 

 right angle. 



18. An oltuse angle is greater than 

 a right angle. 



1 9. Superficies are either plane or curved. 



20. A ^lane superficies ^ or a plane ^ is that, with which a 

 right line may, every way, coincide. But if not, it is 

 curved, 



21. Plane figures are bounded either by right lines 

 or curves. 



22. Plane figures, bounded by right lines, have names 

 according to the number of their sides, or angles ; for 

 they have as many sides as angles ; the least number being 

 three. 



23. A 



