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8th Grade > Mathematics

UNDERSTANDING QUADRILATERALS MCQs

Total Questions : 464 | Page 3 of 47 pages
Question 21.
Every rhombus is a trapezium.
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False
Atrapeziumis a quadrilateral with exactly one pair of parallel sides.
A rhombusis a parallelogram having all sides equal.
Question 22.
The angle between the two altitudes of a parallelogram through the vertex of an obtuse angle of the parallelogram is 45∘. Find the angles of the parallelogram.
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Let ABCD be a parallelogram, where BE and BF are the perpendicular through the vertex B to the sides DC and AD, respectively.
The Angle Between The Two Altitudes Of A Parallelogram Throu...
Let ∠A=∠C=x,∠B=∠D=y [∵ opposite angles are equal in parallelogram]
Now, ∠A+∠B=180∘ [∵ adjacent sides of a parallelogram are supplementary]
⇒x+∠ABF+∠FBE+∠EBC=180∘
⇒x+90∘−x+45∘+90∘−x=180∘
[∵InΔABF,∠ABF=90∘−xandinΔBEC,∠EBC=90∘−x]
⇒−x=180∘−225∘⇒x=45∘∴∠A=∠C=45∘∠B=45∘+45∘+45∘=135∘⇒∠D=135∘
Hence the angles are 45∘,135∘,45∘,135∘.
Question 23.
In parallelogram PQRS, O is the mid-point of SQ. Find ∠S,∠R, PQ, QR and diagonal PR.
In Parallelogram PQRS, O Is The Mid-point Of SQ. Find ∠S,â...
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Given, ∠RQY=60∘
∠SRQ=∠RQY [SR∥PY, RQ is the transversal]
⇒∠R=60∘
∴∠S=180∘−∠R=180∘−60∘=120∘ [∵ adjacent angles are supplementary]
Also, SR = 15 cm
⇒ PQ = 15 cm [∵ opposite sides of a parallelogram are equal]
And PS = 11 cm
⇒ QR = 11 cm [∵ opposite sides of a parallelogram are equal]
PR is bisected by SQ, so PR=2×PO=2×6=12cm
Question 24.
The diagonals of a rhombus are 8 cm and 15 cm. Find its side.
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Given, AC = 15 cm, BD = 8 cm.
The Diagonals Of A Rhombus Are 8 Cm And 15 Cm. Find Its Side...
Since, the diagonals of a rhombus bisect each other at 90∘, therefore in the ΔAOB, we have
AB2=OA2+OB2⇒AB2=(152)2+(82)2=(7.5)2+(4)2=56.25+16⇒AB2=72.25⇒AB=√72.25⇒AB=8.5cm
Since it is a rhombus, the length of each side is 8.5 cm.
Question 25.
If only one diagonal of a quadrilateral bisects the other, then the quadrilateral is known as .
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Kite
In a kite, one diagonal of a the quadrilateral bisects the other.
Question 26.
Two adjacent angles of a parallelogram are in the ratio 1 : 5. Then, all the angles of the parallelogram are
a) 30,150,30,150
b) 85,95,85,95
c) 45,135,45,135
d) 30,180,30,180
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Let the adjacent angles of a parallelogram be x and 5x, respectively.
Then, x+5x=180 [ adjacent angles of a parallelogram are supplementary]
6x=180
x=30
The adjacent anlges are 30 and 150.
Hence, the angles are 30,150,30,150 . [ opposite angles are equal]
Question 27.
In a quadrilateral PQRS, P=50,Q=50,R=60. Find S. Is this quadrilateral convex or concave?
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Given a quadrilateral PQRS, where
P=50,Q=50 and R=60
Now, by the angle sum property of a quadrilateral, we have
P+Q+R+S=36050+50+60+S=360S=360160S=200
One interior angle of the given quadrilateral is greater than 180, therefore the quadrilateral is concave.
Question 28.
To construct a unique rectangle, the minimum number of measurements required is
(a) 4
(b) 3
(c) 2
(d) 1
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Since, in a rectangle, opposite sides are equal and parallel, so we need the measurement of only two adjacent sides, i.e. length and breadth. Also, each angle measures 90.
Hence, we require only two measurements to construct a unique rectangle.
Question 29.
 Is A Closed Curve Entirely Made Up Of Line Segments. The An... is a closed curve entirely made up of line segments. The another name for this shape is ___.
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Concave polygon
As one interior angle is of greater than 180∘.
Question 30.
A rectangle MORE is shown below.
A Rectangle MORE Is Shown Below.Answer The Following Questio...
Answer the following questions by giving appropriate reason.
Is ∠MYO=∠RXE?
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Yes, ∠MYO=∠RXE
Here, MY and RX are perpendicular to OE.
Since, ∠RXO=90∘⇒∠RXE=90∘ and ∠MYE=90∘⇒∠MYO=90∘.

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