An isosceles triangle has a top angle of 75 degrees and a base angle of 75 degrees.
一个等腰三角形，顶角是75度，一个底角是多少度．
<gadget id="calculator">180 - 75</gadget>
<output>105</output>

<gadget id="calculator">105 / 2</gadget>
<output>105/2 = around 52.5</output>

<result>105/2 = around 52.5</result>