Page:An introduction to linear drawing.djvu/39

 ﻿may measure the radius with his dividers, and then ap- ply them to each side of the hexagon. In other words, the cord of an arc, which is the sixth part of a circle, is equal to a radius or half diameter, (usually called a semi-diameter.)

22. Cut a circle into three equal parts, and inscribe an equilateral triangle, (fig. 13.)

After the hexagon is correctly drawn by problem 21st, it is easy to inscribe the triangle required in this, by drawing a cord between two points of the hexagon.

If cords be then drawn between the three remaining points of the hexagon, another triangle will be formed, whose base will be opposite the base of the other trian- gle, forming a beautiful figure resembling a star.

23. Make two unequal circles tangent outside.

nequal circles are circles of unequal size only.

24.	Make two unequal circles tangent inside, (fig.15.)

25.	The centres and the point of contact being giv- en, perform problems 23 and 24.

The monitor will mark the centres, he. When the circles touch either within or without, the point of con- tact and the two centres will be in a right line, and these may be tested with a rule.

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14.)