Special Edition - KCC's Quiz - World Engineering Day Quiz - What's the area of the ring?

We have :  \text{Aring}=\pi\times(R^2-r^2)

Since the length of the half string is 1 meter, we have:

1+r^2=R^2

Therefore :

A\text{ring=\textbackslash pi}

We have :  \text{Aring}=\pi\times(R^2-r^2)

Since the length of the half string is 1 meter, we have:

1+r^2=R^2

Therefore :

A\text{ring=\textbackslash pi}

Right MikeLh , congrats!