The base angle of an isosceles triangle is 42°, what is the apex angle?
一个等腰三角形的底角是42°，它的顶角是多少．
<gadget id="calculator">42 * 2</gadget>
<output>84</output>

<gadget id="calculator">180 - 84</gadget>
<output>96</output>

<result>96</result>