Geometry - Cheat sheet

1. Acute Angle : An angle whose measure is between 0 and 90 degree
2. Obtuse Angle : An angle whose measure is greater than 90 but less than 180 degree
3. Right Angle : An angle whose measure is 90 degree
4. Straight Angle : An angle whose measure is 180 degree
5. An angle whose measure is 2 right angle is a straight angle
6. The sum of all angles of a triangle is 180 degree
7. An interior angle is an angle inside a shape
8. An Exterior Angle is the angle between any side of a shape, and a line extended from the next side
9. The sum of exterior and interior angle is 180 degree
10. The side opposite to the right angle of a right angled triangle is called Hypotenuse
11. The radius of a circle is half of its diameter
12. The radii of a circle will always have the same length. They start from the center of the circle and ends on the circumference of the circle
13. The diameter of a circle is twice the radius of the circle
14. A chord is a line segment   that joins two points on a curve. In geometry, a chord is often used to describe a line segment joining two endpoints that lie on a circle
15. Any portion of the circumference of a circle is called ARC
16. A chord that passes through the center of the circle is the diameter of the circle
17. Diameter is the longest chord
18. Every diameter is a chord but not every chord is a diameter
19. Every diameter will be of equal length
20. A line segment has 2 end points
21. A ray has one end point and no definite length
22. A line has no end points
23. Divider and scale are used to compare line segments