CBSE Class 10 Mathematics Basic 2024: question 16
Set in the CBSE Class 10 board exam of 2024, paper 430/5/1, section A, question 16, for 1 mark. Try it first; the hints and our step-by-step solution are below.
Q16 · 1 mark · MCQCircles
AP and AQ are tangents drawn from an external point A to a circle with centre O and inclined to each other at an angle of . If the length of each tangent is 2 cm, then the radius of the circle is :
- (A)4 cm
- (B)2 cm
- (C) cm
- (D)1 cm
Figure in the paper: Circle with centre O. External point A on the left with two tangent segments AP and AQ, each labelled 2 cm. P and Q are the points of contact on the circle; the angle at A is marked . Radii OP and OQ are drawn to the points of contact, and O is joined to the circle's centre. See it in the official paper.
Source: official question paper from cbse.gov.in (PDF). See it in the full 2024 board paper, set 430/5/1.
Hints
Open one hint at a time and try again before the next.
Hint 1
What angle does a radius make with the tangent at the point of contact?
Hint 2
All four angles of APOQ are and adjacent sides AP, AQ are equal.
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.
In APOQ, , [tangent ⟂ radius], so and APOQ is a rectangle with , i.e. a square.
- 1 mark
Hence radius cm.
Answer: 2 cm, option (B)
Where the marks are
- Recognises APOQ as a square, radius = 2 cm (1 mark)
Revise the chapter
- Chapter: Circles (notes, formulas, where marks are lost and every past question)
- Topic: Solving Problems Using Tangent Properties
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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.