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8th Grade > Mathematics

UNDERSTANDING QUADRILATERALS MCQs

Total Questions : 464 | Page 2 of 47 pages
Question 11. Which of the following is true?
  1.    All parallelograms are kites
  2.    All kites are parallelograms
  3.    Some kites are parallelograms
  4.    None of the above
 Discuss Question
Answer: Option C. -> Some kites are parallelograms
:
C
The kites that have all the sides equal and twopairs of sides parallel are parallelograms. These kites are rhombuses.
Hence, some kites are parallelograms.
Question 12. There is a pair of parallel lines which intersects with another pair of parallel lines. The quadrilateral formed is trapezium.
  1.    True
  2.    False
  3.    CD & BC
  4.    AB & CD
 Discuss Question
Answer: Option B. -> False
:
B
The quadrilateral formed between two pairs of parallel lines is a parallelogram. In a trapezium, the only one pair of opposite sides is parallel.
Question 13. Which of the following is/are concave quadrilaterals?
Which Of The Following Is/are Concave Quadrilaterals?
  1.    I & III   
  2.    II & IV    
  3.    IV  
  4.    II     
 Discuss Question
Answer: Option C. -> IV  
:
C
Which Of The Following Is/are Concave Quadrilaterals?
A line segment connecting any two non-consecutive vertices of a polygon is known as diagonal.A polygon with an exterior diagonal is known as concave polygon.
Which Of The Following Is/are Concave Quadrilaterals?
Only in these two options, there exists an exterior diagonal. So, these are concave polygons. But II is a concave pentagon. Only IV is a concave quadrilateral. Moreover, a concave polygon hasone or more interior angle greater than 180°.
Question 14.
Which of the following is a property of a parallelogram?
a) Opposite sides are parallel
b) The diagonals bisect each other at right angles
c) The diagonals are perpendicular to each other
d) All angles are equal
 Discuss Question

:
We know that, in a parallelogram, opposite sides are parallel and equal.
The diagonals bisect each other but not always at right angles.
The diagonals are not perpendicular to each other in allparallelograms.
All angles are equalin allparallelograms.
Hence, option (a) is correct.

Question 15.
Construct a parallelogram POUR in which PO = 5.5 cm, OU = 7.2 cm and O=70.
 Discuss Question

:
Since,
Construct A Parallelogram POUR In Which PO = 5.5 Cm, OU = 7....
We have ,
PO = RU = 5.5 cm, OU = RP = 7.2 cm
(Since the opposite sides of a parallelogram are equal)
Steps of Construction
Step I Draw PO = 5.5 cm.
Step II Construct POX=70.
Step III With O as centre and radius OU = 7.2 cm, draw an arc.
Step IV With U as centre and radius UR = 5.5 cm, draw an arc.
Step V With P as centre and radius PR = 7.2 cm, draw an arc to cut the arc drawn in Step IV.
Step VI Join PR and UR.
Hence, POUR is the required parallelogram.
Question 16.
Construct a trapezium ABCD in which ABDC,A=105, AD = 3 cm, AB = 4 cm and CD = 8 cm.
 
 Discuss Question

:
We know that.
A+D=180 [ sum of adjacent angle of a trapezium is 180]
105+D=180
D=75
Construct A Trapezium ABCD In Which AB∥DC,∠A=105∘, AD ...
Steps of Construction
Step I Draw AB = 4 cm.
Step II Draw ¯AX such that BAX=105.
Step III Mark a point D on AX such that AD = 3 cm.
Step IV Draw ¯DY such that ADY=75.
Step V Mark a point C such that CD = 8 cm.
Step VI Join BC.
Hence, ABCD is the required trapezium.
Question 17.
Find the maximum number of acute angles which a convex quadrilateral, a pentagon and a hexagon can have. Observe the pattern and generalise the result for any polygon.
 Discuss Question

:
Let us assume that a convex polygon has four or more acute angles. If an interior angle is acute, then the corresponding exterior angle will be obtuse ( greater than 90). So, the sum of the exterior angles of such a polygon will begreater than 4×90=360.
However, this is impossible, since the sum of the exterior angles of a polygon must always be equal to 360. Hence, a polygon can have, at most, 3 obtuse exterior angles.
Question 18.
A parallelogram PQRS is constructed with sides QR = 6 cm, PQ = 4 cm and PQR=90. Then, PQRS is a
a) Square
b) Rectangle
c) Rhombus
d) Trapezium
 
 Discuss Question

:
We know that, if in a parallelogram one angle is of 90, then all angles will be of 90 and a parallelogram with all angles equal to 90 is called a rectangle.
Question 19.
In rectangle PAIR, find ARI,RMI and PMA.
In Rectangle PAIR, Find ∠ARI,∠RMI And ∠PMA.
 Discuss Question

:
Given, RAI=35.
PRA=35 . [PRAI and AR is transversal]
ARI=90PRA=9035=55.
RM=IM,MRI=MIR=55.
In ΔRMI,
RMI+MRI+MIR=180 . [Angle sum property]
RMI=1805555=180110=70
Also, PMA=RMI[vertically opposite angles]
PMA=70
Question 20.
The adjacent sides of a parallelogram are 5 cm and 9 cm. Its perimeter is ___.
 Discuss Question

:
28 cm
Perimeter of a parallelogram = 2(Sum of lengths of adjacent sides)
=2(5+9)=2×14=28cm.

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