What is the base angle of an isosceles triangle with a vertex angle of 74°?
一个等腰三角形，顶角是74°，它的一个一底角是多少．
<gadget id="calculator">180 - 74</gadget>
<output>106</output>

<gadget id="calculator">106 / 2</gadget>
<output>53</output>

<result>53</result>