In an isosceles triangle, one vertex angle is 80°, what is the value of each base angle?
等腰三角形中，一个顶角是80°，每个底角是多少°．
<gadget id="calculator">180 - 80</gadget>
<output>100</output>

<gadget id="calculator">100 / 2</gadget>
<output>50</output>

<result>50</result>