Page 168 - ICSE Math 6

4. Write True or False.

(a) An angle has two arms.
(b) A reflex angle is always greater than a complete angle.
(c) Sum of angles around a point is always 180° B

(d) The unit for measuring an angle is degree.

C A
5. Classify each of the angles shown in the given figure as O
acute, right, obtuse, straight or reflex.

D
6. Classify the following pairs of angles as congruent, supplementary or complementary.

(a) 75° and 15° (b) 120° and 60° (c) 30° and 30°
(d) 99° and 81° (e) 27° and 27° (f) 43° and 47° A

7. In the figure given alongside, identify all vertically opposite angles, C O D
adjacent angles and linear pairs.

B
8. Find the number of right angles turned through by the hour hand of a clock when it goes from:
(a) 3 to 9 (b) 5 to 2 (c) 1 to 7
9. The hour hand of a clock starts from 2 and turns through 7 right angles. Where will it stop?

10. A car moves towards east. If on a roundabout it turns anticlockwise towards north, through what
angle does it turn?

Measurement of a Line Segment
A line segment can be measured by:
(i) A ruler (ii) A divider and a ruler

By ruler: A ruler has centimetres marked on one side and inches on the other side. Each centimetre
mark is subdivided into 10 equal divisions. Each small division of a centimetre is called a millimetre.
Let’s learn how to measure a line segment AB.
(a) Put the ruler in such a way that its ‘0’ marking is placed on one of the end points.

(b) Now place the edge of the ruler along the line AB.
(c) Read the marking on the ruler which coincides with the other end point. This measure gives
the length of the line segment AB. For example, the measure of the line segment AB shown
below is 4 cm.
A B

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