In an isosceles triangle, one base angle is 64°, what is the apex angle?
在等腰三角形中，一个底角是64°，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>