An isosceles triangle has a vertex angle of 80°, what is the base angle?
等腰三角形一个顶角为80°，则底角为多少°
<gadget id="calculator">180 - 80</gadget>
<output>100</output>

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

<result>50</result>