The circumference of circle A is (2/3) the circumference of circle B, then the area of circle A is equal to the area of circle B.
甲圆的周长是乙圆周长的(2/3)，则甲圆的面积是乙圆面积的多少．
<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<result>4/9 = around 0.444444</result>