2017 · Q81
An arc of a circle subtends an angle π at the centre. If the length of the arc is 22 cm, then what is the radius of the circle ? (Take π = 22/7)
Elementary MathematicsCircles
- A5 cm
- B7 cm
- C9 cm
- D11 cm
Explanation
For a circle, arc length l = rθ with θ in radians. An angle of π radians is a straight angle (180°), so the given arc is a semicircle of length 22 cm. Substituting: 22 = r × π, so r = 22/π. With π taken as 22/7, r = 22 ÷ (22/7) = 7 cm. The neat integer result confirms the semicircular reading. Hence option (B) 7 cm.