The central angle of a sector is 90°. If the radius is 2 cm, what is the perimeter of the sector in cm?
一个扇形的圆心角为90°．半径为2cm，则这个扇形的周长为多少cm．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">3.14 * 2 * 2 * (1/4)</gadget>
<output>3.14</output>

<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<gadget id="calculator">3.14 + 4</gadget>
<output>7.14</output>

<result>7.14</result>