SCERT AP 7th Class Maths Solutions Pdf Chapter 4 Lines and Angles Ex 4.2 Textbook Exercise Questions and Answers.

## AP State Syllabus 7th Class Maths Solutions 4th Lesson Lines and Angles Exercise 4.2

Question 1.

Observe the given figure and write any 2 linear pairs of angles.

Answer:

Linear pair of angles :

∠KOQ, ∠QOP

∠KOQ, ∠KOL

∠KOL, ∠LOP

∠QOP, ∠POL

∠KOM, ∠MOP

∠QOM, ∠MOL

Question 2.

Draw a pair of adjacent angles which are complementary to each other.

Answer:

In the figure ∠AOB, ∠BOC are adjacent angles and their sum is complementary.

∴ ∠AOB + ∠BOC = 50° + 40° = 90°

Question 3.

Draw a pair of adjacent angles which are supplementary to each other.

Answer:

In the figure ∠POQ, ∠OOR are linear pair and adjacent angles and their sum is supplementary.

∴ ∠POQ + ∠OOR = 110° + 70° = 180°

Question 4.

Give any two examples of adjacent angles in your surroundings.

Answer:

Fan, Bullock cart wheel, Clock, etc.

Question 5.

Observe the figure and write the adjacent angles.

Answer:

In the given figure, adjacent angles are

∠AOC, ∠COB

∠AOC, ∠COD

∠COD, ∠DOB

∠AOD, ∠DOB

Question 6.

Is it possible for the following pair of angles to form a linear pair? If yes, draw them. If not, give reason.

(i) 120°, 60°

Answer:

Yes.

120° + 60° = 180°

120°, 60° (Linear pair)

(ii) 98°, 102°

Answer:

No, their sum is not equal to 180°

98° + 102° = 200° > 180°

So, they are not 1irear pair.

Question 7.

Draw the following angles as linear pair. Write the straight line and common arm.

Answer:

∠BOA + ∠AOC = 180°

∴ ∠BOA and ∠AOC are linear pair.

BC is a straight line and OA is an arm.

Question 8.

In the given figure, AB is a straight line. O is a point on AB . Find the value of x.

Answer:

In the given figure \(\overrightarrow{\mathrm{AB}}\) is a straight line.

∠AOC + ∠COB = 180°

⇒ 2x + 30° + x = 180°

⇒ 3x + 30°= 180°

⇒ 3x + 30° – 30°= 180°

⇒ 3x = 150°

⇒ \(\frac{3 x}{3}=\frac{150^{\circ}}{3}\)

⇒ x = 50

Question 9.

Teacher asked students to check whether 40° and 140° form a linear pair or not by drawing angles. The students have drawn as follows. Who will get correct answer?

Answer:

Raheem: ∠AOD = 140°, ∠BOC = 40° they are not adjacent angles and not linear pair.

So, Raheem is not correct.

Mary: ∠COD = 140°, ∠BOC = 40° they are adjacent angles, but they are not linear pair.

So, Mary answer is not correct.

Roshitha: ∠XOZ = 140°, ∠ZOY = 40° they are adjacent angles and linear pair.

So, Roshitha answer is correct.