CBSE Class 10 Mathematics Basic 2023: question 33(a)
Set in the CBSE Class 10 board exam of 2023, paper 430/5/1, section D, question 33(a), for 5 marks. Try it first; the hints and our step-by-step solution are below.
Q33(a) · 5 marks · Long answerAreas Related to Circles
In the given figure, AB is a chord of a circle of radius 7 cm and centred at O. Find the area of the shaded region if . Also, find length of minor arc AB.
Figure in the paper: A circle with centre O. A chord AB is drawn, with OA and OB joined to form at the centre. The region between chord AB and the minor arc AB below it is shaded. See it in the official paper.
Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 430/5/1.
Hints
Open one hint at a time and try again before the next.
Hint 1
The shaded region is a segment: sector minus triangle.
Hint 2
Since ∠AOB = 90°, the triangle AOB is right-angled with legs equal to the radius.
Hint 3
Arc length = .
Step-by-step solution
Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.
- 1 mark
Area of sector AOB
- ½ mark
cm² cm²
- 1 mark
Area of right cm²
- 1 mark
Area of shaded segment = sector − triangle cm²
- 1½ marks
Length of minor arc AB cm
Answer: Shaded area = 14 cm²; minor arc AB = 11 cm
Where the marks are
- Sector area formula with substitution (1 mark)
- Sector area = 77/2 cm² (½ mark)
- Area of triangle AOB = 49/2 cm² (1 mark)
- Shaded area = 14 cm² (1 mark)
- Arc length = 11 cm (1½ marks)
Revise the chapter
- Chapter: Areas Related to Circles (notes, formulas, where marks are lost and every past question)
- Topic: Area of a Sector of a Circle
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The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.