If the measure of the vertex angle of an isosceles triangle is 70°, what is the measure of the base angle of the triangle?
一个等腰三角形顶角的度数是70°，这个三角形的一个底角的度数是多少．
<gadget id="calculator">180 - 70</gadget>
<output>110</output>

<gadget id="calculator">110 / 2</gadget>
<output>55</output>

<result>55</result>