NCERT Solutions: Shapes and Angles

Page 16

Q1: Mohini made this.
Now you give the answers.
(i) Is it a closed shape?
Sol: Yes, it is a closed shape.
(ii) Does it have 6 sides?
Sol: Yes, it has 6 sides. But it is not the same as the one made by Rohini.

Q2: Mohini tried again.
This is what she made.
(i) Is it a closed shape with 6 sides?
Sol: Yes, it is a closed shape with 6 sides.
(ii) Is it the same as the one made by Rohini?
Sol: No, it is not the same as the one made by Rohini.
(iii) Is there some way to say in what way these shapes are different?
Sol: These shapes are different in angles.
(iv) Look at the angles marked in these shapes. Can you see the difference?

Sol: By seeing the figure, we can say that the each figure has different shape and different angels.

Page 17-18

Q1: Look at the shape and answer.

(i) The angle marked in colour is the biggest angle.
Sol: The angle marked in black colour is the biggest angle.

Q2:

(i) Are the angles marked with yellow equal?
Sol: Yes, the angles marked with yellow are equal.
(ii) Are the angles marked with green equal?
Sol: Yes, the angles marked with green are equal.
(iii) Are the angles marked with blue equal?
Sol: Yes, the angles marked with blue are equal.

Q3: Four different angles are marked in four colours. Can you find other angles which are the same as the one marked in red? Mark them in red do this for other colours.

Sol: 

The angle marked in yellow is same as the one marked in red.
All angles of the hexagon are same as the angle marked in green.
All angles of the octagon are same as the angle marked in black. 

Q4: How many different shapes can you make by changing the angle between the matchsticks in each of these? Try.
Sol: Following shapes can be made by changing angles.
You can increase the number of matchsticks to make more shapes.

Page 19

Q1: Make 8 triangles using 6 matchsticks. Try! 
Sol: 

Q2: Take 8 matchsticks and make a fish like this. Now pick up any 3 matchsticks and put them in such a way that the fish now starts swimming in the opposite direction. Did it? 

Sol:

Q3: Using 10 matchsticks make this shape. Pick any 5 matchsticks and put them in such a way that you get the shape of a house. 

Sol: 

Page 20

Angle Tester 
Q1: How do we make equal angles? 
Sol: We can use the divider from the geometry box to make equal angles. Measure an angle with the help of the divider and make another angle of equal measurement. The divider is also called the angle tester.

Q2: How can you make your own angle tester? 

Sol: For this, you need following materials; cardboard strips, drawing pins or split pin.Take two cardboard strips of same size. Join their one ends with the help of the drawing pin or split pin. Move the strips from joint so that they can freely rotate. Your angle tester is ready.

Page 21

Q1: Sukhman made this picture with so many angles.
Use colour pencils to mark.
(i) right angles with black colour.
(ii) angles which are more than a right angle with green.
(iii) angles which are less than a right angle with blue.
Sol: In the given picture: 
(i) Right angles are shown by the letter ‘R’. 
(ii) Angles which are more than the right angle are shown by the letter ‘O’. 
(iii) Angles which are less than the right angle are shown by the letter ‘L’.

Q2: Draw anything of your choice around the angle shown. Also write what kind of angle it is. The first one is done.

Sol: Hint: The purpose of this section is to make students observe their surroundings. It is highly recommended that the students prepare the answers on their own.

Page 25

Q1: Write 3 names using straight lines and count the angles.

Name	Number of right angles	Number of angles more than a right angle	Number of angles less than a right angle

Sol: 

Name	Number of right angles	Number of angles more than a right angle	Number of angles less than a right angle
MEERA	8	3	6
REENA	8	2	3
BALLAN	2	4	4

Page 26

Q1: These are two slides in a park.

(i) Which slide has a larger angle?
Sol: The slide which comes in the right of the boy has larger angle.

(ii) Which slide do you think is safer for the little boy? Why?
Sol: The slide which comes in right is safer. Because, slide on the left of the boy is steeper than the other.

Page 27

Q1:
(i) Find out how many angles are there in each of these shapes. Mark them.

Sol:

(ii) Find out and write your results in the table given.

Sol:

Page 28-29

Q1: There are many times in a day when the hands of a clock make a right angle. Now you draw some more.

Sol:

Q2: Write what kind of angle is made by the hands at these times. Also write the time.

Sol:

Q3: Draw the hands of the clock when they make an angle which is less than a right angle. Also write the time.

Sol:

Q4: Can you guess how many degrees is the angle which is?
(i) ½ of a right angle .
Sol:
We know that the right angle is equal to 90 degrees.
Then, ½ of a right angle = ½ × 90 degrees.
= 1 × 45
= 45^o

(ii) 1/3 of a right angle .
Sol:
We know that the right angle is equal to 90^o.
Then, 1/3 of a right angle = 1/3 × 90^o
= 1 × 30
= 30^o

(iii) 2 times of a right angle.
Sol:
We know that the right angle is equal to 90^o.
Then, 2 times of a right angle = 2 × 90^o
= 180^o