GSEB Class 6 Maths Solutions Chapter 5 Understanding Elementary Shapes InText Questions

Try These (Page 88)

Question 1. Take any post card. Use the above technique to measure its two adjacent sides.
Answer: Do it yourself.

Exam Tip: Practical activities like this help in understanding geometric concepts through direct experience. Always try to perform them.

Question 2. Select any three objects having a flat top. Measure all sides of the top using a divider and a ruler
Answer: Do it yourself.

Exam Tip: When using a divider and ruler, ensure accurate placement and reading to get precise measurements. Practice makes perfect for these fundamental skills.

Try These (Page 91)

Question 1. What is the angle name for half a revolution?
Answer: Two straight angles equal one full revolution.
\( \frac { 1 }{ 2 } \) [2 straight angles] \( = \frac { 1 }{ 2 } \) [1 revolution]
So, a straight angle means \( \frac { 1 }{ 2 } \) revolution.
Therefore, half a revolution is called a straight angle.
In simple words: When something turns exactly halfway around, it has made a straight angle, which is half of a full turn.

Exam Tip: Remember that a full circle is \( 360^\circ \), so half a revolution is \( 180^\circ \), which is indeed a straight angle.

Question 2. What is the angle name for one-fourth revolution?
Answer: Four right angles make up one full revolution.
A right angle \( = \frac { 1 }{ 4 } \) revolution
Hence, one-fourth of a revolution is known as a right angle.
In simple words: When something turns a quarter of the way around, it creates a right angle, like the corner of a square.

Exam Tip: A right angle is \( 90^\circ \), and \( 90^\circ \) is exactly one-fourth of \( 360^\circ \), confirming this definition.

Question 3. Draw five other situations of one-fourth, half and three-fourth revolution on a clock
Answer:
(i) One-fourth revolution (i.e., a turn of a right angle)
For one-fourth revolution, the clock hand moves from:
(a) 12 to 3
(b) 3 to 6
(c) 1 to 4
(d) 9 to 12
(e) 6 to 9

(ii) Half-revolution (i.e., a turn of a straight angle)
For a half-revolution, the clock hand moves from:
(a) 12 to 6
(b) 3 to 9
(c) 1 to 7
(d) 4 to 10
(e) 6 to 12

(iii) Three-fourth revolution (i.e., a turn of 3 right angles)
Note: There is no special name for three-fourth of a revolution.
For a three-fourth revolution, the clock-hand moves from:
(a) 12 to 9
(b) 3 to 12
(c) 6 to 3
(d) 9 to 6
(e) 1 to 10

Exam Tip: To draw these clock diagrams correctly, always start by placing the clock numbers accurately. Then, draw the hour hands to represent the starting and ending positions, and finally, shade the angle or indicate the rotation with an arc.

Question 1. The hour hand of a clock moves from 12 to 5. Is the revolution of the hour hand more than I right angle?
Answer: Yes, the movement of the hour hand from 12 to 5 o'clock covers more than one right angle.

Exam Tip: A right angle on a clock face represents a movement of 3 hours (e.g., from 12 to 3). Moving from 12 to 5 means passing 3 hours (12 to 3) plus an additional 2 hours (3 to 5), which is clearly more than one right angle.

Question 2. What does the angle made by the hour hand of the clock look like when it moves from 5 to 7? Is the angle moved more than I right angle?
Answer: No, in this situation, the angle formed is less than a right angle.

Exam Tip: A movement of less than 3 hours on a clock face will always result in an angle smaller than a right angle. From 5 to 7 is only a 2-hour movement, making it an acute angle.

Question 3. Draw the following and check the angle with your RA tester.
(a) going from 12 to 2
(b) from 6 to 7
(c) from 4 to 8
(d) from 2 to 5
Answer:
(a) Going from 12 to 2: The angle formed by the hour hand moving from 12 to 2 is shown in the figure alongside. Checking this angle with a right angle tester, we find that it is less than a right angle.

(b) Going from 6 to 7: Checking the angle formed by a right angle tester, we find that it is less than a right angle.

(c) Going from 4 to 8: Checking the angle formed by a right angle tester, we find that it is greater than a right angle.

(d) Going from 2 to 5: Checking the angle formed by a right angle tester, we find that it is equal to a right angle.

Exam Tip: To quickly check angles, recall that each hour mark on a clock is \( 30^\circ \). A right angle is \( 90^\circ \), so it spans 3 hour marks. Use this to estimate angles before using a tester.

Question 4. Take five different shapes with corners. Name the corners. Examine them with your tester and tabulate your results for each case:
Answer:

It is an activity. Do it yourself.

Exam Tip: When tabulating results, be consistent in how you describe or mark whether an angle is smaller or larger than a right angle. Accuracy in measurement is key for these observations.

Try These (Page 94)

Question 1. Look around you and identify edges meeting at corners to produce angles. List ten such situations.
Answer: Do it yourself.

Exam Tip: Observe common objects like tables, doors, windows, and books. Their corners are excellent examples of angles formed by meeting edges.

Question 2. List ten situations where the angles made are acute.
Answer: Do it yourself.

Exam Tip: An acute angle is less than a right angle. Think about clock hands at certain times (e.g., 1 o'clock), open scissors, or the tip of a pencil.

Question 3. List ten situations where the angles made are right angles.
Answer: Do it yourself.

Exam Tip: Right angles are very common. Look at the corners of rooms, books, windows, or the intersection of walls and the floor.

Question 4. Find five situations where obtuse angles are made.
Answer: Do it yourself.

Exam Tip: An obtuse angle is larger than a right angle but less than a straight angle. Examples include a clock at 4 o'clock, the angle formed by an open laptop screen, or an open door at a certain point.

Question 5. List five other situations where reflex angles may be seen.
Answer: Do it yourself.

Exam Tip: A reflex angle is greater than a straight angle (\( 180^\circ \)) but less than a full revolution (\( 360^\circ \)). Think of an analog clock at 8 o'clock, observing the larger angle formed by the hands, or the angle of a bending elbow if it could bend backwards.