1. Index  Introduction of angleIntroduction of angle  Types of angles Types of angles  Exercise Exercise

2. Yesterday we have studied about the angles. Today, we will study about the types of angles. Before continuing today's class we will discuss little bit about the angle. In mathematics, if two rays start from the same point, the figure so formed is called an angle. Examples - Next ExitHome

3. Above fig. shows angle ABC. The point where the rays intersect is called the vertex of the angle. Here B is vertex. The two rays are called the arms of the angle. Here BA and BC are arms of angle ABC. A (Vertex) B C arm (Vertex) B A NextBack ExitHome

4. There are five types of angles:- 1)Acute angleAcute angle 2)Right angleRight angle 3)Obtuse angleObtuse angle 4)Straight angleStraight angle 5)Reflex angleReflex angle TYPES OF ANGLES ExitHome NextBack

5. Acute angle- An angle whose measure is more than 0 but less than 90 is called an acute angle. Given angle AOB measures 60, which is less than 90. So, it is an acute angle. OO A B60 NextBack ExitHome Acute angle

6. Right angle- An angle whose measure is 90 is called a right angle. Given angle POQ measures 90. So, it is a right angle. P O Q P O Q NextBack ExitHome

7. Obtuse angle – An angle whose measure is more than 90 but less than 180 is called an obtuse angle. Given angle PQR measures 120, which is more than 90 but less than 180. So, it is an obtuse angle. P Q R 120 NextBack ExitHome

8. Straight angle – An angle whose measure is 180 is called a straight angle. Given angle BOD measures 180. So, it is a straight angle. D BOD 180 NextBack ExitHome

9. Reflex angle – An angle whose measure is more than 180 but less than 360 is called a reflex angle. Given angle PQR measures 225. So, it is a reflex angle. 225 P QR NextBack ExitHome Exit

10. Exercise 1)An angle whose measure is between 0 and 90 is called angle. (a) acute (b) right (c) obtuse NextBack ExitHome

11. 2)An angle whose measure is 90 is called angle. (a) acute (b) right (c) obtuse NextBack ExitHome

12. 3) An angle whose measure is more than 90 but less than 180 is called angle. (a) acute (b) right (c) obtuse NextBack ExitHome

13. 4) A reflex angle is always greater than but less than 360. (a) 0 (b) 90 (c) 180 NextBack ExitHome

14. 5) Which of the following is an acute angle- (a) 45 (b) 120 (c) 305 NextBack ExitHome

15. 6) What is the measure of straight angle- (a) 90 (b) 180 (c) 360 NextBackExitHome

16. 7) Which of the following is reflex angle- (a) 150 (b) 60 (c) 320 Back ExitHomeExitHome