In a right triangle, the ratio of the two acute angles is 2:7, what is the smallest angle?
一个直角三角形，两个锐角度数的比是2：7，最小的角是多少度．
<gadget id="calculator">2 + 7</gadget>
<output>9</output>

<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">90 * (2/9)</gadget>
<output>20</output>

<result>20</result>