Page 51 - Ganit Kaushal

4. State the type of the angles whose measures are given below:
(a) 67° (b) 127° (c) 90° (d) 180°
(e) 225° (f) 342° (g) 88° (h) 179°
5. Identify the acute, obtuse and reflex angles represented by small letters in the following figures.

(a) (b) (c)

6. Find the degree measure of ∠AXB, ∠EXD,
∠DXC, ∠CXB, and ∠DXB in the given adjacent
figure.

7. The Ashok Chakra on the Indian flag is navy blue and represents the Dharma Chakra or Wheel of
Law created by the 3rd-century Mauryan Emperor Ashoka. It contains 24 spokes. What is the degree
of the angle formed by two adjacent spokes?
8. Using a protractor, draw angles of 65 degrees, 75 degrees, 110 degrees, 135 degrees and 170 degrees.
2.8 ANGLES RELATED TO HANDS OF A CLOCK

There are 12 equal parts on a clock face. These 12 parts together make a full circle (1 full turn or 1 revolution).
Therefore, each part is made up of an angle, i.e.,
1
× 360° = 30°.
12
The minute hand moves 12 times faster than the hour hand.
In an hour, the hour hand moves 30° and the minute hand moves 12 × 30° = 360° (i.e., 1 full
turn). The hands of a clock make different angles at different times.
At 1 o’clock (see adjoining figure), the angle between the two hands is 30°, because of the
above-mentioned reason.

Understanding Directions and Rotations

There are four main directions, North, East, South, and West, denoted by their initials, i.e., N, E, S, and W.

There are two senses of rotation – clockwise and anticlockwise sense of rotation, as
shown in the given figure.
East and West are at right angles to North and South. East is in the clockwise direction of
rotation from North, and West is directly opposite to East. We can also define directions
between them.
For example, the South-East direction (SE) is the direction that makes an angle of 45°
with E in an anticlockwise sense and with S in a clockwise sense.

Lines and Angles 49