If the diameter of the base of a cone is 10 cm and the height is 9 cm, if it is cut into two equal parts along the diameter of the base, what is the increase in the surface area in square centimetres?
圆锥的底面直径是10cm，高是9厘米，沿底面直径切成两个完全相等的部分，表面积增加多少平方厘米．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">10 * 9 * (1/2) * 2</gadget>
<output>90</output>

<result>90</result>