Page 95 - Maths Skill - 6

Lines and Angles 93

Exercise 6.3

1. What are the measures of (i) a right angle? and (ii) a straight angle?

2. Say whether True or False.
(i) The measure of an acute angle < 90°. (ii) The measure of an obtuse angle < 90°.
(iii) The measure of a reflex angle > 180°. (iv) The measure of one complete revolution = 360°.

3. Write down the measures of.
(i) some acute angles. (ii) some obtuse angles.

(Give at least two examples of each.)
4. Fill in the blanks with ‘acute’, ‘obtuse’, ‘right’ or ‘straight’.
(i) An angle whose measure is less than that of a right angle is ___________.

(ii) An angle whose measure is greater than 90° but less than 180° is ___________.

(iii) An angle whose measure is the sum of the measures of two right angles is ___________.

(iv) When the sum of the measures of two angles is that of a right angle, then each one of them is ___________.
(v) When the sum of the measures of two angles is that of a straight angle and if one of them is acute then

the other should be ___________.
5. State the kind of angle that is formed between the following directions.

(i) East and North (ii) North and South (iii) East and West (iv) South and West
6. How many degrees are there in an angle between the hands of a clock when it is.

(i) 12 o’clock (ii) 9 o’clock (iii) 6 o’clock (iv) 3 o’clock
7. Calculate how many degrees are there in.

1 4
(i) right angle (ii) three right angles (iii) right angle (iv) four right angles
2 3
8. Classify the following angles in acute, obtuse or reflex angle.

(i) 70° (ii) 135° (iii) 240° (iv) 95°

(v) 17° (vi) 207° (vii) 300° (viii) 160°
9. By using protractor to draw angles having the following degree measures :

(i) 130° (ii) 80° (iii) 100° (iv) 230° (v) 56°
10. In each of the below grids, join A to other grid points in the figure by a straight line to get :
(a) An acute angle

A B