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CBSE Class 10 Basic Math 2025 All Sets Solved Paper

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Question : 16 of 20
Marks: +1, -0
An arc of length 'l' subtends an angle of 15∘15^{\circ} at the centre of a circle of radius 8.4 cm. The value of l is
Solution:  
The length of an arc is given by the formula
l=rθ,l=r \theta,
where r is the radius and θ is the angle in radians.
Convert the angle from degrees to radians:
15∘15^{\circ}
=15∘×π180=15^{\circ} \times \frac{\pi}{180}
=π12 radians= \frac{\pi}{12} \text{ radians}
∴l=rθ\therefore l=r \theta
=8.40 cm×π12=8.40 \text{ cm} \times \frac{\pi}{12}
=8.4 cm×22712=8.4 \text{ cm} \times \frac{\frac{22}{7}}{12}
=8.4×2212×7 cm= \frac{8.4 \times 22}{12 \times 7} \text{ cm}
=2210 cm= \frac{22}{10} \text{ cm}
=2.2 cm=2.2 \text{ cm}
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