An isosceles triangle has a perimeter of 1 meter and a waist of 0.4 meters. How long is the base of this triangle?
一个等腰三角形周长1米，腰长是0.4米，这个三角形底边长多少米？
<gadget id="calculator">0.4 * 2</gadget>
<output>0.8</output>

<gadget id="calculator">1 - 0.8</gadget>
<output>0.2</output>

<result>0.2</result>