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9th Grade > Mathematics

LINES AND ANGLES MCQs

Lines And Angles

Total Questions : 74 | Page 7 of 8 pages
Question 61.


 In the figure given below, if OP || RS, ∠OPQ = 110o and ∠QRS = 130o, then ∠PQR is equal to


 In The Figure Given Below, If OP || RS, ∠OPQ = 110o And...


  1.     60
  2.     65
  3.     40
  4.     45
 Discuss Question
Answer: Option A. -> 60
:
A

Extend OP. Then, a triangle PQT will be formed; where T is the point at which OP cuts QR.


 In The Figure Given Below, If OP || RS, ∠OPQ = 110o And...


Now,


OPQ + QPT = 180


QPT = 180 - 110 = 70


Now, since if OP || RS,  SRQ and UTQ are corresponding angles hence, UTQ = SRQ = 130


Therefore we have,


UTQ + PTQ = 180


PTQ = 180 - 130 = 50


In triangle PTQ,


PTQ + TQP + QPT = 180


50 TQP + 70 = 180


TQP = 180 - 120 = 60


TQP = PQR = 60


Question 62.


With reference to the figure below, consider the two statements:


Statement 1: The points A, B, and C will lie on a straight line if x + y = 180.


Statement 2: The angle on a straight line is 180.


With Reference To The Figure Below, Consider The Two Stateme...


  1.     Both the statements are true and statement 2 is the correct explanation of statement 1.
  2.     Both the statements are true and statement 2 is not the correct explanation of statement 1.
  3.     Statement 1 is true and statement 2 is false.
  4.     Statement 1 is false and statement 2 is true.
 Discuss Question
Answer: Option A. -> Both the statements are true and statement 2 is the correct explanation of statement 1.
:
A

The angle on a straight line is 180. Adjacent angles on a straight line add up to 180.


Conversely, if adjacent angles add up to 180 then the angles are on a straight line.


Hence, if x + y = 180 , then A, B and C lie on a straight line.


Therefore, both the statements are true and statement 2 is the correct explanation of statement 1.


Question 63.


Two parallel lines have: 


  1.     A common point
  2.     Two common points
  3.     No common point
  4.     Infinite common points
 Discuss Question
Answer: Option C. -> No common point
:
C

Two Parallel Lines Have: 
Parallel lines never intersect. Hence, they have no common point.


Question 64.


Assume line m and line n are parallel lines cut by the transversal line l.  Find the value of x.


Assume Line M And Line N Are Parallel Lines Cut By The Trans...


  1.     45
  2.     25
  3.     5
  4.     60
 Discuss Question
Answer: Option B. -> 25
:
B

Since, the sum of co-interior angles (interior angles on the same side) = 180


x + 15 + 6x - 10 = 180


7x + 5 = 180


7x = 175


x = 25


Question 65.


If one angle of a triangle is equal to the sum of the other two angles which are equal, then the triangle is a/an _________ .


  1.     Acute angled triangle
  2.     Obtuse angled triangle
  3.     Right angled triangle
  4.     Equilateral triangle
 Discuss Question
Answer: Option C. -> Right angled triangle
:
C

Let the two equal angles be x.


Then the third angle y = 2x


Also we know,
y + 2x = 180°  (Sum of the angles of a triangle is 180°)


2x + 2x = 180°                              


4x = 180°


x = 45°


Hence the two equal angles are 45° each and the other angle is 90° which makes this triangle a right angled triangle.


Question 66.


The angle between the bisectors of two adjacent supplementary angles is a right angle.


  1.     True
  2.     False
  3.     Right angled triangle
  4.     Equilateral triangle
 Discuss Question
Answer: Option A. -> True
:
A

Let A and B be adjacent supplementary angles as shown in the figure.
The Angle Between The Bisectors Of Two Adjacent Supplementar...
Then, A+B=180
The bisectors of the angles are drawn. We have to find 1+2.
1+2=(A2+B2)
=1802=90
Hence, the angle between the bisectors of adjacent supplementary angles is 90.


Question 67.


Which of the following are true?


  1.     A triangle can have two right angles.
  2.     A triangle can have all angles less than 60
  3.     A triangle can have two acute angles.
  4.     A triangle cannot have two obtuse angles.
 Discuss Question
Answer: Option C. -> A triangle can have two acute angles.
:
C and D

The sum of the three angles of a triangle should be 180. Hence it cannot have two right angles. If it has all angles less than 60 then they cannot add up to form 180. A triangle can have two or three acute angles. It cannot have two obtuse angles because then the sum of the three angles would be greater than 180.


Question 68.


Two angles whose measures are a & b are such that 2a - 3b = 60 then 5b =


___
degrees, if they form a linear pair.
 Discuss Question
Answer: Option C. -> A triangle can have two acute angles.
:

Given that,


 2a - 3b = 60


Also if they form a linear pair, then


2 × (180 - b) - 3b = 60      ( since  a = 180 - b)


⇒ 360 - 2b - 3b = 60


⇒ 5b =300


Question 69.


An angle 'x' is 14 more than its complement. Find the angle.


  1.     38
  2.     52
  3.     50
  4.     104
 Discuss Question
Answer: Option B. -> 52
:
B

The sum of two complementary angles is 90.
If one angle is x, then another angle will be 90x.
x(90x)=14
                   2x=104
                     x=52


Question 70.


Angles of a triangle are in the ratio 2 : 4 : 3. The smallest angle of the triangle is


  1.     40
  2.     30
  3.     60
  4.     80
 Discuss Question
Answer: Option A. -> 40
:
A

The sum of all the three angles of a triangle = 180


Since the angles are in the ratio 2 : 4 : 3, let x be a factor such that,


2x + 4x + 3x=180


=> 9x = 180


=> x = 20


Hence the three angles of the triangle are:


=> 2x = 40


=> 4x = 80


=> 3x = 60


So the smallest angle in the given triangle is 40.


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