Question

What is the length of a circular curve when θ is in degrees and ‘r’ is the radius?

(a) s = rθ

(b) s = r

(c) \(s = \frac{πrθ}{180} \)

(d) s = πr

This question was addressed to me in final exam.

The origin of the question is Rectification topic in chapter Integral Calculus of Engineering Mathematics

Answer 1

Right choice is (c) \(s = \frac{πrθ}{180} \)

The explanation: Degrees must be converted to equivalent radians and therefore the arc length is found considering both the radius and angle.