Area Moment of inertia of a circular wire

1. Mar 5, 2010

Hlw.....I am a new guy here.....And I am taking a course of Applied Mechanics in my freshmen year....Here I have come across a term called Area of moment of inertia which I don't really understand that much........And I have been given to prove that
$$I_d = \frac{\pi a^4}{4}$$......I was trying everything but I am at my wit's end.......So, if some helps me it would be great.......A thanks in advance for the help....

2. Mar 5, 2010

tiny-tim

Welcome to PF!