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A piece of wire 20 cm long is… (Class 10 Maths 2025, Q18)

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MathsCBSE Class 10 · Standard · Board exam 2025, set 30/1/1 · 1 mark · MCQ

CBSE Class 10 Mathematics Standard 2025: question 18

Set in the CBSE Class 10 board exam of 2025, paper 30/1/1, section A, question 18, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q18 · 1 mark · MCQCompetency-basedAreas Related to Circles

A piece of wire 20 cm long is bent into the form of an arc of a circle of radius cm. The angle subtended by the arc at the centre of the circle is :

  1. (A)
  2. (B)
  3. (C)
  4. (D)

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 30/1/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

The wire's length is the arc length.

Hint 2

Use . Notice that cancels.

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. Arc length . So .

  2. , so the answer is option (B).

    1 mark

Answer: , option (B)

Where the marks are

  • Uses the arc-length formula to get , option (B) (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Areas Related to Circles, one at a time, marked against the answer key and marking points.Back to the full paper2025 board paper, set 30/1/1 (Standard): every question, by section.

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.