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NCERT Class XI Mathematics - Trigonometric Functions - Solutions

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Question : 5 of 61
Marks: +1, -0
In a circle of diameter 40 cm, the length of a chord is 20 cm. Find the length of minor arc of the chord.
Solution:  
Let AB be the minor arc of the chord.
AB = 20 cm, OA = OB = 20 cm
⇒ DOAB is an equilateral triangle.
⇒ ∠AOB = 60°
Now, 1° = (π180)\left(\frac{\pi}{180}\right) radians ⇒ 60° = π3\frac{\pi}{3} radians
Also , l = rθ ⇒ l = 20 × π3\frac{\pi}{3} = 20π3\frac{20\pi}{3} cm
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