Class 6 Maths Understanding Elementary Shapes Angles-‘Right’ and ‘Straight’

Angles-‘Right’ and ‘Straight’

There are four directions in Geography. These are: East(E), West(W), North(N) and South(S).

If we take a turn from North to East, then it is a right angle.

Again take the turn from north to south by two right angles is called a straight line.

The one complete turn is called one revolution. The angle for one revolution is a complete angle. When hand of a clock moves from one position to another, it is called an angle.

Problem:

What fraction of a clockwise revolution does the hour hand of a clock turn through, when it goes from

(a) 3 to 9                   (b) 4 to 7                  (c) 7 to 10             (d) 12 to 9               (e) 1 to 10             (f) 6 to 3

Solution:

We may observe that in 1 complete clockwise rotation, the hour hand will rotate by 3600

(a) When the hour hand goes from 3 to 9 clockwise, it will rotate by 2 right angles or 1800

So, Fraction = 180/360 = 1/2

(b) When the hour hand goes from 4 to 7 clockwise, it will rotate by 1 right angle or 900

So, Fraction = 90/360 = 1/4

(c) When the hour hand goes from 7 to 10 clockwise, it will rotate by 1 right angle or 900

So, Fraction = 90/360 = 1/4

(d) When the hour hand goes from 12 to 9 clockwise, it will rotate by 3 right angles or 2700

So, Fraction = 270/360 = 3/4

(e) When the hour hand goes from 1 to 10 clockwise, it will rotate 3 right angles or 2700

So, Fraction = 270/360 = 3/4

(f) When the hour hand goes from 6 to 3 clockwise, it will rotate 3 right angles or 2700

So, Fraction = 270/360 = 3/4

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