Amplitude of 3-kg Pendulum 2m Arc 21.4°

[ebola_virus]

A pendulum has a mass of 3-kg, a length of 2 meters and swings through a (half)arc of 21.4 degrees. What is its Amplitude to the nearest centimeter ?

i don't undretand the queston; half arc? amplitude?

and how would you use kinetic/potential energy change to solve this porblem? i really don't understand this qusetion i'd really likea couple of hints and tips for this problem thanks a lot

 

[neo143]

74.66 cm
arc=radius*angle