If a base angle of an isosceles triangle is 74°, what is its apex angle?
一个等腰三角形的一个底角是74°，那么它的顶角是多少．
<gadget id="calculator">74 * 2</gadget>
<output>148</output>

<gadget id="calculator">180 - 148</gadget>
<output>32</output>

<result>32</result>