A wolf dog is tied to an iron pile by a 5-meter-long iron chain by its owner. Later, the owner increases the iron chain by 2 meters. At this time, how many square meters does the wolf dog's defense range increase?
一只狼犬倍主人用一根5米长的铁链拴在铁桩上，后来主人将铁链增加2米，这时狼犬的防卫范围增加了多少平方米？
<gadget id="calculator">5 + 2</gadget>
<output>7</output>

<gadget id="calculator">7 ** 2</gadget>
<output>49</output>

<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">49 - 25</gadget>
<output>24</output>

<gadget id="calculator">3.14 * 24</gadget>
<output>75.36</output>

<result>75.36</result>