A pendulum has a mass of 2.7 kg, a length of 1.7 meters, and swings through a (half)arc of 22.7 degrees. What is its amplitude to the nearest centimeter?

Answer 1

Well, normally we measure amplitude of a pendulum in degrees, so the amplitude written this way would be

Theta=22.7*Cos(2PI*t/Period)
and amplitude is 22.7 deg.

Now with all the data you gave, and asking for amplitude in cm, then measured from the center of mass, the ARC length measurement is 1.7*2PI*22.7/360 and some would call that amplitude.