An image should appear at this position in the text.To use the entire page scan as a placeholder, edit this page and replace "{{missing image}}" with "{{raw image|An introduction to linear drawing.djvu/25}}". Otherwise, if you are able to provide the image then please do so. For guidance, see Wikisource:Image guidelines and Help:Adding images. |

20. *Make an acute angle.* (fig. 7.)

Care must be taken to distinguish an *angle*, from what is called its *point* or *apex*. The *angle* is the *opening* between two lines that meet, and the *point* or *apex* is the point where the lines meet. A pair of dividers forms a number of different angles, by being opened more or less.

It is this *opening* of the sides which determines the size of the angle, and not the *length* of the sides, which, if lengthened out ever so far, would not affect the size of the angle, because the opening will only be the same part of a a great circle that it was of a small one.

An image should appear at this position in the text.To use the entire page scan as a placeholder, edit this page and replace "{{missing image}}" with "{{raw image|An introduction to linear drawing.djvu/25}}". Otherwise, if you are able to provide the image then please do so. For guidance, see Wikisource:Image guidelines and Help:Adding images. |

Imagine two lines which cross each other as in figures 9 and 10. They will make four angles. These are *right* angles if they are *equal*, and they will be equal if one line is perpendicular to the line it crosses. If the angle be *less* than a *right* angle, it is called an *acute* angle; if more, it is called an obtuse angle. *Acute* means sharp, and *obtuse* means blunt.

21. *Make an obtuse angle.* (fig. 8.)

22. *Make an acute angle with the opening turned upward, downward, to the right and to the left.*

23. *Make a triangle.* (fig. 11.)