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NCERT Class XI Mathematics - Trigonometric Functions - Solutions

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Question : 5
Total: 61
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° = (
π
180
) radians ⇒ 60° =
π
3
 radians
Also , l = rθ ⇒ l = 20 ×
π
3
 =
20π
3
 cm
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