The ratio of the top angle to the base angle of an isosceles triangle is 4:1, what is the base angle?
等腰三角形的顶角与底角的比是4：1，它的底角是多少度．
<gadget id="calculator">4 + 1 + 1</gadget>
<output>6</output>

<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">180 * (1/6)</gadget>
<output>30</output>

<result>30</result>