Class 6 Maths Chapter 5 Understanding Elementary Shapes Exercise 5.2 pdf notes:-
Exercise 5.2 Class 6 maths Chapter 5 Pdf Notes:-
Ncert Solution for Class 6 Maths Chapter 5 Understanding Elementary Shapes Exercise 5.2 Tips:-
Angles – ‘Right’ and ‘Straight’
You have heard of directions in Geography. We know that China is to the
north of India, Sri Lanka is to the south. We also know that Sun rises in the
east and sets in the west. There are four main directions. They are North (N),
South (S), East (E) and West (W).
Do you know which direction is opposite to north?
Which direction is opposite to west?
Just recollect what you know already. We now use this knowledge to learn
a few properties about angles.
Stand facing north.
Turn clockwise to east.
We say, you have turned through a right angle.
Follow this by a ‘right-angle-turn’, clockwise.
You now face south.
If you turn by a right angle in the anti-clockwise
direction, which direction will you face? It is east
From facing north to facing south, you have turned by
two right angles. Is not this the same as a single turn by
two right angles?
The turn from north to east is by a right angle.
The turn from north to south is by two right angles; it
is called a straight angle. (NS is a straight line!)
Stand facing south.
Turn by a straight angle.
Which direction do you face now?
You face north!
To turn from north to south, you took a straight angle
turn, again to turn from south to north, you took another
straight angle turn in the same direction. Thus, turning by
two straight angles you reach your original position.
Think, discuss and write
By how many right angles should you turn in the same direction to reach your
Turning by two straight angles (or four right angles) in the same direction
makes a full turn. This one complete turn is called one revolution. The angle
for one revolution is a complete angle.
We can see such revolutions on clock-faces. When the
hand of a clock moves from one position to another, it turns
through an angle.
Suppose the hand of a clock starts at 12 and goes round
until it reaches at 12 again. Has it not made one revolution?
So, how many right angles has it moved? Consider these
From 12 to 6 From 6 to 9 From 1 to 10
2 of a revolution.
4 of a revolution
4 of a revolution
or 2 right angles. or 1 right angle. or 3 right angles.