Naughty bought an isosceles triangle kite. Its top angle is 40°, what is one of its bottom angles?
淘气买了一个等腰三角形的风筝．它的顶角是40°，它的一个底角是多少？
<gadget id="calculator">180 - 40</gadget>
<output>140</output>

<gadget id="calculator">140 / 2</gadget>
<output>70</output>

<result>70</result>