a pendulum of length (L) = 1m swings through an angle 20 deg. What is the length (d) of the path traveled by the pendulum mass?
20º is 1/18 of a circle (20/360)
the length of the arc is
... 1/18 * 2 * π * 1 m
the length of the arc is
... 1/18 * 2 * π * 1 m