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23 Cards in this Set

  • Front
  • Back
What is a point?
1. A point is that which has no part.
What is a line?
2. A line is breadthless length.
What are the extremities of a line?
3. The extremities of a line are points.
What is a straight line?
4. A straight line is a line which lies evenly with the points on itself.
What is a surface?
5. A surface is that which has length and breadth only.
What are the extremities of a surface?
6. The extremities of a surface are lines.
What is a plane surface?
7. A plane surface is a surface which lies evenly with the straight lines on itself.
What is a plane angle?
8. A plane angle is the inclination to one another of two lines in a plane which meet one another and do not lie in a straight line.
What is a rectilineal angle?
9. And when the lines containing the angle are straight, the angle is called rectilineal.
What is a right angle / perpendicular line?
10. When a straight line set up on a straight line makes the adjacent angles equal to one another, each of the equal angles is right, and the straight line standing on the other is called a perpendicular to that on which it stands.
What is an obtuse angle?
11. An obtuse angle is an angle greater than a right angle.
What is an acute angle?
12. An acute angle is an angle less than a right angle.
What is a boundary?
13. A boundary is that which is an extremity of anything.
What is a figure?
14. A figure is that which is contained by any boundary or boundaries.
What is a circle?
15. A circle is a plane figure contained by one line such that all straight lines falling upon it from one point among those lying within the figure are equal to one another.
What is the point at the center of a circle called?
16. The point is called the centre of the circle.
What is the diameter of the circle?
17. A diameter of the circle is any straight line drawn through the centre and terminated in both directions by the circumference of the circle, and such a straight line also bisects the circle.
What is a semicircle?
18. A semicircle is the figure contained by the diameter and the circumference cut off by it. And the centre of the semicircle is the same as that of the circle.
What is a rectilineal figure? A trilateral figure? A quadrilateral? A multilateral?
19. Rectilineal figures are those which are contained by straight lines, trilateral figures being those contained by three, quadrilateral those contained by four, and multilateral those contained by more than four straight lines.
What is an equilateral triangle? An isosceles? A scalene?
20. Of trilateral figures, an equilateral triangle is that which has its three sides equal, an isosceles triangle that which has two of its sides alone equal, and a scalene triangle that which has its three sides unequal.
What is a right-angle triangle? An obtuse? An acute?
21. Further, of trilateral figures, a right-angled triangle is that which has a right angle, an obtuse-angled triangle that which has an obtuse angle, and an acute-angled triangle that which has its three angles acute.
What is a square? An oblong? A rhombus?
22. Of quadrilateral figures, a square is that which is both equilateral and right-angled; an oblong that which is right-angled but not equilateral; a rhombus that which is equilateral but not right-angled; and a rhomboid that which has its opposite sides and angles equal to one another but is neither equilateral nor right-angled. And let quadrilaterals other than these be called trapezia.
What is parallel?
23. Parallel straight lines are straight lines which, being in the same plane and being produced indefinitely in both directions, do not meet one another in either direction.