Elements of constructive geometry.pdf

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Excerpt from book: ELEMENTS OF CONSTRUCTIVE GEOMETRY. I. LINES. 1. Draw a free-hand line (i.e. without ruler) upon the blackboard or paper, making it, according to your judgment, one inch in length. Compare its length with an inch measure. Note. — All lines not otherwise designated are to be considered straight. 2. Draw free-hand lines two, three, four, etc., inches in length, and compare their lengths with the corresponding measures. 3. Draw a free-hand line of given length, and compare it with its corresponding measure: then bisect it and trisect it, and compare the lengths of the divisions. 4. Draw lines of various lengths, divide them into two. three, four, five, six, etc., equal parts, and compare the parts of each. 5. Suspend a small weight from, the end of a cord, and draw a line on the blackboard that shall take the same direction as the cord. What name is applied to lines that take this direction ? 6. What name is applied to a line that takes the direction of the surface of standing water ? What is the difference between horizontal and level ? 7. Draw a vertical line and a horizontal line upon the blackboard. Can you draw a line that is neither horizontal nor vertical ? Draw such a line. What name is applied to it? 8. If I should mark a point upon the blackboard, and ask you to draw a line through it, would you know what direction it should take ? If I should mark two points, and tell you to draw a line through them, would you know in what direction to draw it ? How many points are necessary to determine the direction 6f a straight line ? Would more points be of any service ? In either case, why ? 9. What name would you give to a line made partly of straight and partly of curved parts ? What, to one made of straight parts taking different directions ? 10...  

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