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