The apex angle of an isosceles triangle is 50°, what is the base angle?
等腰三角形顶角是50°，底角应是多少°．
<gadget id="calculator">180 - 50</gadget>
<output>130</output>

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

<result>65</result>