The apex angle of an isosceles triangle is 30°, what is the base angle?
一个等腰三角形顶角是30°，一个底角为多少°
<gadget id="calculator">180 - 30</gadget>
<output>150</output>

<gadget id="calculator">150 / 2</gadget>
<output>75</output>

<result>75</result>