If the ratio of the degrees of two adjacent interior angles of an isosceles triangle is 1:2, what is the base angle of the triangle?
一个等腰三角形的相邻两个内角的度数比是1：2，那么这个三角形的底角是多少．
<gadget id="calculator">1 + 1 + 2</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>