If a cone with a height of 4 cm is cut along the diameter and height of the base, the surface area increases by 36 cm2 compared to the original one. What is the volume of the cone?
把一个高是4厘米的圆锥沿底面直径和高切开，表面积比原来增加了36平方厘米，这个圆锥的体积是多少？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">36 / 2</gadget>
<output>18</output>

<gadget id="calculator">2 / 4</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">18 * (1/2)</gadget>
<output>9</output>

<gadget id="calculator">9 / 2</gadget>
<output>9/2 = around 4.5</output>

<gadget id="calculator">(9/2) ** 2</gadget>
<output>81/4 = around 20.25</output>

<gadget id="calculator">(1/3) * 3.14 * (81/4) * 4</gadget>
<output>84.78</output>

<result>84.78</result>