The ratio of the apex angle to the base angle of an isosceles triangle is 2:1, what is the apex angle in degrees?
一个等腰三角形的顶角与一个底角的比是2：1，它的顶角是多少度．
<gadget id="calculator">2 + 1 + 1</gadget>
<output>4</output>

<gadget id="calculator">2 / 4</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">180 * (1/2)</gadget>
<output>90</output>

<result>90</result>