The base angle of an isosceles triangle is 64°, what is the apex angle?
一个等腰三角形的底角是64°，它的顶角是多少．
<gadget id="calculator">64 * 2</gadget>
<output>128</output>

<gadget id="calculator">180 - 128</gadget>
<output>52</output>

<result>52</result>