Point:- A point has no length, breadth or thickness.
Line:- line has no fixed length and no breath for thickness.
Line segment:- a line segment has length but no breadth or thickness.
Ray:- The part of the line in which one point is fixed and the other point is uncertain, is called a ray.
Angle:- Two line segments or rays with the common end-point form an angle.
* When two line segments or rays meet at the same end point, it is called an angle.
1. Acute Angle - An angle whose measure is between 0 and 90 degrees is called acute angle.
(An angle less than 90 degrees.)
0⁰ < X < 90⁰
2. Right Angle - An angle whose measure is 90 degree is called right angle.
(An angle that is exactly 90 degrees.)
X = 90⁰
3. Obtuse Angle - An angle whose measure is between 90⁰ and 180⁰ is called an obtuse angle.
(An angle more than 90⁰ and less than 180⁰.)
90⁰ < X <180⁰
4. Straight Angle - An angle whose measure is 180⁰ is called a straight angle.
(An angle that is exactly 180 degrees.)
X = 180⁰
5. Reflex angle:- An angle whose measure is greater than 180⁰ but always less than 360⁰ is called a reflex angle.
180⁰ < X <360⁰
6. Complete angle:- An angle whose measure is 360⁰ is called complete angle.
.....................x...................
Complementary and supplementary angle
* The sum of two angles equal to 90⁰ is called complementary angle.