What is the apex angle of an isosceles triangle with a base angle of 65°?
一个等腰三角形，一个底角是65°顶角是多少．
<gadget id="calculator">65 * 2</gadget>
<output>130</output>

<gadget id="calculator">180 - 130</gadget>
<output>50</output>

<result>50</result>