# Important Questions for Class 7 Chapter 5-Lines and Angles

Students, you may need to practice a lot while preparing for CBSE board exams and other exams. However, how do you decide on the questions or topics to prepare for? For your benefit, our Math subject experts have meticulously prepared a list of important questions for CBSE class 7 Math chapter-wise and topic-wise.

Important questions based on NCERT syllabus for Class 7 Chapter 5 - Lines and Angles:

Question 1: Find out the unknown ∠BOD in the given quadrilateral ABDC in which AB || CD. Given that AD& BC is angle bisector of ∠BAC & ∠DCA respectively.

Solution:
Since AB||CD therefore sum of opposite interior angle is equal to 180⁰ ∠BAC +∠DCA = 180°
Since AD& BC divide the angle in two equal parts, therefore sum ∠OAC &∠ACO is also half of the sum of ∠BAC & ∠DCA which is equal to 90⁰.
So ∠AOC = 180°- 90°= 90°(sum of all the angles in triangle is 180⁰)
∠AOC = ∠BOD = 90⁰ (Vertically Opposite Angles).

Question 2: In the given figure, find the value of ∠BAC.∆DEF is equilateral, ∠CBA =40°, ∠FEC =50° and DE is parallel to BC.

Solution:
Given in question DE||BC, so ∠ADE =∠DBF= 40⁰(corresponding angle)
∠AED = 180⁰- (50⁰+60⁰) = 70⁰ (Linear pair of angles)
∠AED = ∠ECB=70⁰ (Corresponding Angles);
Now consider ∆ADE having ∠AED & ∠ADE is equal to 70⁰ and 40⁰ respectively.
For determining the ∠DAE = 180⁰- (70⁰+40⁰) = 70⁰.

Question 3: In the given figure prove that lx||my || nz.

Solution:
∠xpb=∠msp= K (Alternate Angles are equal),
So, lx|| my.
∠psm=∠srn =K (Corresponding Angles),
So, my||nz.
As we know that, if, lx||my and my||nz,
So, lx||my||nz.