An isosceles triangle billboard, one of its top angles is 50°, how many degrees is its bottom angle?
一个一块等腰三角形广告牌，它的一个顶角是50°，它的底角是多少度？
<gadget id="calculator">180 - 50</gadget>
<output>130</output>

<gadget id="calculator">130 / 2</gadget>
<output>65</output>

<result>65</result>