$\"\"$

\

The radius of the large circle is $\"\"$ .

\

From the graph:

\

The equation of the large circle is $\"\"$ .

\

Draw the related diagram:

\

$\"\"$

\

Observe the diagram:

\

The center of the small circle is $\"\"$ .

\

The equation of the small circle is $\"\"$ .

\

The area of the lune $\"\"$ .

\

$\"\"$

\

$\"\"$

\

Apply formula : $\"\"$ .

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

$\"\"$

\

The area of the lune is $\"\"$ .

\

$\"\"$

\

The area of the lune is $\"\"$ .