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Math Olympiad Test: Circles- 1 - Free MCQ with solutions Class 9 Mathematics


MCQ Practice Test & Solutions: Math Olympiad Test: Circles- 1 (10 Questions)

You can prepare effectively for Class 9 Mathematics Olympiad for Class 9 with this dedicated MCQ Practice Test (available with solutions) on the important topic of "Math Olympiad Test: Circles- 1". These 10 questions have been designed by the experts with the latest curriculum of Class 9 2026, to help you master the concept.

Test Highlights:

  • - Format: Multiple Choice Questions (MCQ)
  • - Duration: 10 minutes
  • - Number of Questions: 10

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Math Olympiad Test: Circles- 1 - Question 1

The largest chord of a circle is called its:

Detailed Solution: Question 1

The largest chord of a circle is called diameter of the circle.

Any chord which crosses the centre of the circle is the largest chord of the circle, which is the diameter of the circle.

Math Olympiad Test: Circles- 1 - Question 2

AB and CD are two parallel chords of a circle such that AB = 8 cm, and CD = 6cm. If the chords are on the opposite sides of the center and the distance between them is 7cm, then the diameter of the circle is:

Detailed Solution: Question 2

Let the radius of the circle be r, and the length OP be x

∴ In ∆OPB, 
OP2 + PB2 = OB2 = r2
⇒ x2 + (4)2 = r  [∵ PB = AB/2]
⇒ x2 = r2 – 16 ….(i) 
In ∆OCQ,
OQ2 + CQ2 = r2
⇒  (7 – x)2 + (3)2 = r2
[∵ OQ = PQ - OP = 7 - x]
⇒ (7 – x)2 = r2 – 9 ….(ii)
Subtracting (ii) from (i), we get
x2 – (7 – x)2 = – 7
⇒ (x – 7 + x) (x + 7 – x) = – 7 
⇒    (2x – 7) (7) = – 7  
⇒  (2x – 7) = – 1 
⇒ x = 3
∴ r2 = x2 + 16 [using (i)]
= (3)2 + 16 = 25
⇒ r = 5cm 
∴ d = 10 cm. 

Math Olympiad Test: Circles- 1 - Question 3

Two circles of radii 13cm and 15cm intersect and the length of the common chord is 24 cm, then the distance between their centers is: 

Detailed Solution: Question 3

In ∆OPA, 


Similarly, 
In ∆O′PA,

= 9cm. 
∴ OO′ = OP + O′P = 5 + 9 = 14 cm.

Math Olympiad Test: Circles- 1 - Question 4

Bisector AD of ∠BAC of ∆ABC passes through the center of the circumcircle of ∆ABC, then,

Detailed Solution: Question 4

∵ AD is the bisector of ∠BAC

∴ AD is the ⊥ bisector of BC. 
∵ O is the circumcentre of ∆ABC.
∴ AB = AC [∵ ∠ABD = ∠ACB]
(By using ∆ABD ≅ ∆ACD)

Math Olympiad Test: Circles- 1 - Question 5

Find the measure of ∠ABC.

Detailed Solution: Question 5

Reflex ∠AOC = 360° – (110° + 120°) 
= 130° 

Math Olympiad Test: Circles- 1 - Question 6

The measure of ∠BOC is

Detailed Solution: Question 6

∠BOC = 2 × ∠BAC [Angle subtended at center is double the angle subtended the circle]
= 2 × 30° = 60°

Math Olympiad Test: Circles- 1 - Question 7

P is the center of the circle, and ∠XPZ = 120°, ∠XZY = 35°, then the measure of ∠YXZ is: 

Detailed Solution: Question 7


∠XPY = 2∠XOP
∵ ∠XOP = ∠XZY
(angles in the same segment)
∴ ∠XPY = 2∠XZY …(i)
Similarly, 
∠YPZ = 2∠YXZ …(ii)
Using (i) and (ii)
∠XPZ = 2 (∠XYZ + ∠YXZ)

Math Olympiad Test: Circles- 1 - Question 8

PQRS is a cyclic quadrilateral such that PR is the diameter of the circle. If ∠QPR = 64° and ∠SPR = 31°, then, ∠R =?

Detailed Solution: Question 8


∠P = ∠QPR + ∠SPR
= 64 ° + 31° 
= 95°
∵ ∠Q and ∠S are angles of the semicircle
∴ ∠Q = ∠S = 90° 
∵ PQRS is a cyclic quadrilateral
∴ ∠P + ∠R = 180°
⇒ ∠R = 180° - 95° = 85°

Math Olympiad Test: Circles- 1 - Question 9

If A, B, C are three points on a circle with center O such that ∠AOB = 90° and ∠BOC = 120°, then ∠ABC =?

Detailed Solution: Question 9


Reflex ∠AOC = 360° – (90° + 120°) = 150° 

Math Olympiad Test: Circles- 1 - Question 10

O is the center of the circle, with AC = 30 cm and DA = 10√5 cm, then the measure of DC is 

Detailed Solution: Question 10

In ∆ACD, 
∠ADC = 90° [∵∠ACD is angle in semicircle]
∴  AC2 = DA2 + DC2
⇒ (30)2 = (10√5 )2 + DC2
⇒ DC2 = 900 – 500 
⇒ DC = √400 = 20 cm. 

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