2019 · Q43
A piece of wire is in the form of a sector of a circle of radius 20 cm, subtending an angle 150° at the centre. If it is bent in the form of a circle, then what will be its radius?
Elementary MathematicsCircles
- A19/3 cm
- B7 cm
- C8 cm
- DNone of the above
Explanation
Arc length = 2.pi.x20x150/360 = 50.pi/3. As a circle, 2.pi.r = 50.pi/3 gives r = 25/3 = 8.33 cm, which matches none of the listed values, so 'None of the above'. (Trap: r = 8 looks close but is wrong.)