$\"\"$

Diameters of the circles are in geometric sequence: $\"\"$ .

Therefore, $\"\"$ .

The circumference of a circle is $\"\"$ .

Sequence of circumferences of a circles is $\"\"$

Find the common ratio $\"\"$ .

$\"\"$

Therefore, sequence of circumferences of the circles is also geometric.

The common ratio is $\"\"$ .

$\"\"$

Area of the circle is $\"\"$ .

Sequence of areas of a circles is $\"\"$

Find the common ratio $\"\"$ .

$\"\"$

Thus, sequence of areas of the circles is also geometric with common ratio $\"\"$ .

$\"\"$

(a) Sequence of circumferences of the circles is also geometric with common ratio $\"\"$ .

(b) Sequence of areas of the circles is also geometric with common ratio $\"\"$ .