The DAV Maths Book Class 4 Solutions and DAV Class 4 Maths Chapter 10 Brain Teasers Solutions of Angles offer comprehensive answers to textbook questions.
DAV Class 4 Maths Ch 10 Brain Teasers Solutions
Question 1.
Tick (✓) the correct answer.
(a) The angle made between the hands of a clock at 2 O’ clock is a ___________ angle.
(i) Obtuse
(ii) Acute
(iii) Right
(iv) Straight
Answer:
(ii) Acute
(b) There are ___________ right angles in a straight angle.
(i) 3
(ii) 2
(iii) 1
(iv) 4
Answer:
(ii) 2
(c) The two rays forming an angle are called the ___________ of the angle.
(i) Arms
(ii) Angle
(iii) Degree
(iv) Vertex
Answer:
(i) Arms
(d) An angle of measure equal to ___________ is an obtuse angle.
(i) 89°
(ii) 91°
(iii) 80°
(iv) 81°
Answer:
(ii) 91°
(e) Sum of four angles of a rectangle is equal to degrees.
(i) 180°
(ii) 90°
(iii) 360°
(iv) 100°
Answer:
(iii) 360°
Question 2.
Fill in the blanks.
(a) An angle has ___________ vertex and ___________ arms.
Answer:
One, two
(b) A 75° angle is an ___________ angle.
Answer:
Acute
(c) Each angle of ___________ a rectangle is of degrees.
Answer:
90°
(d) There are ___________ angles in a square.
Answer:
4
(e) There are ___________ angles in a triangle.
Answer:
3
(f) An angle equal to 180° is called a ___________ angle.
Answer:
Straight.
Question 3.
Draw the following angles of any measure.
(a) ∠AOB
Answer:
Let us draw ∠AOB = 55°
(b) ∠XYZ
Answer:
Let us draw ∠XYZ = 90°
(c) ∠MNP
Answer:
Let us draw ∠MNP = 95°
Question 4.
How many angles are there in the following figures?
Answer:
5 angles
Answer:
8 angles
Question 5.
Draw a line segment PQ of length 6 cm. At P draw an angle of measure 60°.
Answer:
Question 6.
Construct the following angles.
(a) 110°
Answer:
(b) 90°
Answer:
(c) 25°
Answer:
(d) 165°
Answer:
Question 7.
Look at the given figure and answer the following.
(a) How many acute angles are there?
Answer:
1
(b) How many obtuse angles are there?
Answer:
2
(c) How many right angles are there?
Answer:
1
(d) Is ∠ABC an acute angle?
Answer:
No
(e) ∠DCB = ___________ degree.
Answer:
90
Question 8.
Look at the letter and complete the table.
Answer:
Question 9.
The hour hand and minute hand of a clock are making an angle of 90° with each other. The time is ___________ O’ clock or ___________ O’ clock.
Answer:
3 O’ clock or 9 O’ clock
Question 10.
Name all the angles in the given figure.
Answer:
∠AOB, ∠BOC, ∠AOC
Question 11.
Compare using ‘>’, ‘<‘ or ‘=’.
(a) Acute angle __ Obtuse angle
(b) Right angle __ Obtuse angle
(c) Straight angle __ Two right angles
Answer:
(a) <
(b) <
(c) =
Additional Questions
Question 1.
Complete the table:
Answer:
| Angle | Arm |
| ∠Q | \( \overrightarrow{\mathrm{PQ}}, \overrightarrow{\mathrm{QR}} \) |
| ∠Y | \( \overrightarrow{\mathrm{XY}}, \overrightarrow{\mathrm{YZ}} \) |
Question 2.
Draw the following angles:
(a) Acute angle ∠MNO.
(b) Obtuse angle ∠PQR.
(c) Right angle ∠LMN.
(d) Straight angle ∠XYZ.
Answer:
(a) Acute angle can be drawn between 0° and 90°.
∠MNO = 60°
(b) Obtuse angle must be greater than 90° or lie between 90° and 180°.
∠PQR = 120°
(c) Right angle
∠LMN = 90°
(d) Straight angle
∠XYZ = 90°
Question 3.
Identify the following angles:
Answer:
(i) Right angle
(ii) Obtuse angle
(iii) Zero angle
(iv) Acute angle
(v) Acute angle
Question 4.
Put ‘<‘, ‘>’ or ‘=’ sign.
(i) Obtuse angle ( ) Acute angle
(ii) Right angle ( ) Two right angles
(iii) Right angle ( ) Acute angle
(iv) Obtuse angle ( ) Zero angle
(v) Straight angle ( ) Zero angle
Answer:
(i) >
(ii) <
(iii) >
(iv) >
(v) >
Question 5.
Name all the angles in figure.
Answer:
∠ABC, ∠CBD, ∠DBE, ∠ABD, ∠CBE, ∠ABE