If the perimeter of the sector is 50cm and the radius is 12cm, what is the area of the sector in cm**2.
如果扇形的周长是50cm，半径是12cm，那么这个扇形的面积是多少cm**2．
<gadget id="calculator">390 * 144</gadget>
<output>56_160</output>

<gadget id="calculator">56_160 / 360</gadget>
<output>156</output>

<result>156</result>