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Q1. A student claims that if a chord subtends an angle of 90° at the centre of a circle, then the area of the minor segment is always equal to the area of the minor sector minus the area of the right triangle formed. Which concept does this claim rely on?
Answer: A — The claim correctly applies the definition: segment area = sector area − triangle area; this is the fundamental relationship from the chapter, not about congruence or triangle properties.
Q2. A rope of length 7 m is tied to a corner of a square field. The horse grazes a quarter-circle of radius 7 m. A teacher says this area represents a 'sector' while another says it is a 'segment'. Who is using the correct term and why?
Answer: A — The grazing area is bounded by two radii (the two sides of the corner) and an arc, which defines a sector; a segment requires a chord, which is not present here.
Q3. Assertion (A): The area of a major sector is always greater than the area of its corresponding minor sector. Reason (R): A major sector has a central angle greater than 180°. Choose the correct option:
Answer: A — Both statements are true: a major sector has angle > 180° (so < 180° for minor), and since area = (θ/360°)πr², larger angle directly implies larger area; R explains why A holds.
Q4. A construction engineer designs a circular tank and marks an arc of 60° from the centre. She needs to find the area between the chord and the arc. Which formula should she use?
Answer: A — The region between a chord and its arc is a segment, defined as sector area minus the triangular area formed by the two radii and chord; option B gives the complementary (major) segment.
Q5. Assertion (A): For a sector with central angle θ, if θ is doubled, the area is also doubled. Reason (R): Sector area is directly proportional to the central angle. Choose the correct option:
Answer: A — Both are true: sector area = (θ/360°)πr², so doubling θ doubles the area; R directly explains A because area is proportional (linear relationship) to angle.
Q6. A student observes that for a given radius, the area of a 120° sector equals the area of a circle of radius r/√2. Is this observation mathematically correct?
Answer: A — Sector area = (120/360)πr² = (1/3)πr²; circle area = π(r/√2)² = (1/2)πr²; these are NOT equal, so the observation is false; option A appears to affirm it but the math shows they differ.
Q7. A farmer ties a 10 m rope to one corner of a rectangular field. The grazing region forms a quarter-circle. If the farmer later moves the tying point to the middle of a side, what happens to the grazing area?
Answer: A — From a corner, only a quarter-circle (90°) can be swept; from a side midpoint (not bounded by two edges meeting at 90°), a semicircle (180°) can be swept; with the same radius, sector area increases with larger central angle.
Q8. Assertion (A): A chord that subtends a 60° angle at the centre creates a minor segment whose area equals (π/6 − √3/4)r². Reason (R): The segment area formula subtracts the equilateral triangle area from the 60° sector area. Choose the correct option:
Answer: C — The segment area formula (sector − triangle) is correct, but a 60° sector with two equal radii forms an isosceles triangle, NOT equilateral; the triangle area is (1/2)r²sin(60°) = (√3/4)r², making A true but R's reasoning about the triangle type is false.
Q9. Two circles have radii 7 cm and 14 cm. A sector of 90° is marked in each. A student claims the larger circle's sector is exactly twice the smaller one. Evaluate this claim using the sector area formula.
Answer: B — Sector area ∝ r²: for radius 7, area = (90/360)π(7)² = (49π/4); for radius 14, area = (90/360)π(14)² = (196π/4) = 4 × (49π/4); doubling radius quadruples area, not doubles it.
Q10. Assertion (A): The area of a major segment is always larger than the area of the minor segment for the same chord. Reason (R): Major and minor segments are complementary regions that together form the complete circle. Choose the correct option:
Answer: A — Both statements are true: major and minor segments partition the circle (R is true), and since the major segment's arc spans > 180°, its area exceeds the minor segment's (A is true); R correctly explains why A holds.
What is the formula for the area of a sector with angle θ (in degrees) and radius r?
Area of sector = (θ/360) × πr², where θ is the angle in degrees and r is the radius.
How do you find the length of an arc in a sector of angle θ?
Arc length = (θ/360) × 2πr, using the same unitary method as sector area.
Define a sector of a circle.
A sector is the region enclosed between two radii and the arc connecting their endpoints.
Define a segment of a circle.
A segment is the region enclosed between a chord and the arc it cuts off.
What is the formula for the area of a segment?
Area of segment = Area of sector − Area of triangle formed by the two radii and chord.
What is the relationship between minor and major sectors?
Minor sector angle + Major sector angle = 360°, and Minor sector area + Major sector area = πr².
If a chord subtends a right angle (90°) at the centre, what is the area of the minor sector?
Area of minor sector = (90/360) × πr² = (1/4)πr², which is called a quadrant.
How do you find the area of a triangle OAB when the two radii OA and OB and angle AOB are known?
Area of triangle OAB = (1/2) × OA × OB × sin(∠AOB) = (1/2)r² sin(θ).
What happens to sector area when the angle is 360°?
When angle = 360°, the sector becomes the entire circle, so sector area = πr².
Why is the unitary method used to derive the sector area formula?
Because a full circle (360°) has known area πr², so any angle θ has proportional area (θ/360) × πr².
Define sector and segment of a circle. State the formula for the area of a sector with angle θ (in degrees) and radius r. [2 marks]
A sector is bounded by two radii and an arc; a segment is bounded by a chord and an arc. Formula: Area = (θ/360) × πr².
A chord of a circle with radius 21 cm subtends an angle of 60° at the centre. Find the area of the minor segment. (Use π = 22/7 and √3 = 1.73) [3 marks]
Calculate sector area using (θ/360) × πr², then find triangle area = (1/2)r² sin(60°), and subtract to get segment area = Sector − Triangle.
A chord of a circle with radius 15 cm subtends an angle of 60° at the centre. Find the areas of both the minor and major segments. Also, verify that both segments together equal the circle's area. (Use π = 3.14 and √3 = 1.73) [5 marks]
For minor segment: compute sector area (θ/360)πr², triangle area = (1/2)r² sin(θ), then subtract. For major segment: use total area πr² minus minor segment. Verify: Minor + Major segment = πr².
Q1. Assertion (A):
The area of a sector with angle 180° and radius r equals half the area of the circle.
Reason (R):
A sector of angle 180° is a semicircle, and its area is (180°/360°) × πr² = (1/2)πr², which is exactly half the circle's area πr².
Answer: A — Both A and R are true, and R is the correct explanation of A — Both the assertion and reason are true. The reason correctly explains the assertion by showing that 180° is exactly half of 360°, making the sector area exactly half the circle area. The mathematical calculation confirms this.
Q2. Assertion (A):
The length of an arc is directly proportional to the central angle of the sector.
Reason (R):
The arc length formula is l = (θ/360°) × 2πr, showing that as θ increases, the arc length increases proportionally.
Answer: A — Both A and R are true, and R is the correct explanation of A — Both assertion and reason are true, and the reason perfectly explains the assertion. The formula clearly shows the direct proportionality relationship between arc length and central angle θ.
Q3. Assertion (A):
The area of a minor segment equals the area of its corresponding sector minus the area of the triangle formed by the two radii and the chord.
Reason (R):
A segment is the region between a chord and an arc, while a sector includes the triangle portion, so removing the triangle from the sector gives the segment.
Answer: A — Both A and R are true, and R is the correct explanation of A — Both assertion and reason are true. The reason correctly explains why we subtract the triangle area from the sector area. The geometric relationship is accurately described.
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Case Study:
A city garden is designed with a circular flower bed of radius 14 m. The garden designer wants to create different sections. One section is a sector with central angle 90° where sunflowers are planted. Another section is a segment created by a chord, with the chord subtending a central angle of 120° where roses are planted. The remaining area has grass. The designer needs to calculate the area for each section to determine the required quantity of seeds and fertilizers.
Q1. What is the area of the sunflower sector (90°)? (Use π = 22/7)
Answer: B
Q2. Calculate the area of the sector where roses are planted (120° angle). (Use π = 22/7)
Answer: A
Q3. For the rose sector (120°), if we need to find just the segment area (between chord and arc), we need to subtract the triangle area. What is the area of the triangle OAB formed by the two radii and chord? (Use √3 = 1.73)
Answer: A
Q4. What is the area of the grass section? Total garden area = πr². (Use π = 22/7)
Answer: B
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Real CBSE board exam questions from past papers — free to attempt.
CBSE 2026 · Set 31/4/1 · 1 mark
Chord AB subtends an angle of 40° at the centre of the circle of radius 9 cm. The length of arc AB is:
CBSE 2026 · Set 31/4/1 · 3 marks
A chord of a circle of radius 14 cm subtends a right angle at the centre. Find the area of the corresponding (i) minor segment (ii) major segment.
CBSE 2026 · Set 31/4/3 · 1 mark
An arc of length 11 cm subtends an angle of 105° at the centre of the circle. The radius of the circle is:
CBSE 2026 · Set 31/4/3 · 3 marks
A circle of radius 12 cm is divided into 11 identical sectors. Find the total area of 7 such sectors.
CBSE 2026 · Set 31/5/2 · 4 marks
In a circular museum hall of radius 14 m, some statues are displayed. Statues are kept inside the inner concentric circle of radius 7 m. One such statue lying in sector OAB, is fenced along line segments OA, AP, PB and BO where P is a point on outer circle.
(i) Find m∠AOP.
CBSE 2026 · Set 31/5/3 · 3 marks
Chord AB of a circle subtends an angle of 120° at the centre O of the circle. Find the length of arc AB, if radius of the circle is 21 cm.
CBSE 2026 · Set 31/5/3 · 1 mark
In a circular museum hall of radius 14 m, some statues are displayed. Statues are kept inside the inner concentric circle of radius 7 m. One such statue lying in sector OAB, is fenced along line segments OA, AP, PB and BO where P is a point on outer circle.
Find m∠AOP.
CBSE 2026 · Set 31/1164/30 · 1 mark
The perimeter of sector of a circle of radius 21 cm and central angle 60, is
CBSE 2026 · Set 31/1164/30 · 1 mark
Assertion (A) : In a circle of radius 21 cm, an arc of length 22 cm subtends an angle of 60° at the centre. Reason (R) : The length of arc of a sector of a circle of radius r and central angle θ is 2πrθ/360.
CBSE 2026 · Set 31/1164/30 · 2 marks
A chord AB of a circle of radius 14 cm makes a right angle at the centre of the circle. Find the area of the minor segment.
CBSE 2026 · Set 31/1167/430 · 1 mark
The area (in cm²) of a sector of a circle of radius 14 cm cut off by an arc of length 22 cm is:
CBSE 2026 · Set 31/1167/430 · 1 mark
The minute hand of a clock is 21 cm long. The distance covered by the tip of minute hand from 2:10 pm to 2:25 pm is:
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