A vertex angle of an isosceles triangle is (1/2) of its base angle, then how many degrees is its base angle.
一个等腰三角形的一个顶角是它一个底角的(1/2)，那么它的底角是多少度．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 + 1 + (1/2)</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">180 / (5/2)</gadget>
<output>72</output>

<result>72</result>