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PART THE FIRST.

PRACTICAL GEOMETRY.

DEFINITIONS.

1. A POINT is the beginning of magnitude, and has neither length, breadth nor thickness.

2. A Line is length without breadth.

3. A Straight Line is the fhortest which can be drawn from one point to another.

4. Parallel Straight Lines are equally distant in all their parts, and if produced ever so far both ways would never meet.

B

5. An Angle is the meeting of two lines in a point, but not fo as to form one straight line.

6. When one Straight Line stands on another and makes the angles on each fide equal, both angles are right angles, and that line which stands on the other is a perpendicular to it.

7. An Obtufe Angle is greater than a right angle.

8. An Acute Angle is fmaller than a right angle.

9. A Circle is a plain figure, bounded by one curved line which is called the circumference, which is every where equally distant from the point C within the circle, called the centre thereof.

C.

10. A Diameter of a Circle is a straight line drawn through the centre, and terminated both ways by the circumference.

11. A Radius of a Circle is a straight line drawn from the centre to the circumference, and is equal to half the diameter.

12. A Semicircle is half a circle, and is contained by half the circumference and a diameter.

13. A Quadrant is a quarter of a circle, and is contained by two radii and a quarter of the circumference.

14. A Segment of a Circle is any part of it cut off by a straight line, as A B C.

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