Divide the bottom surface of a cylinder with a height of 30 centimeters into several sectors on average, then cut the cylinder and assemble it into an approximate cuboid with the same base and height. The surface area of the cuboid is 180 square centimeters larger than that of the original cylinder. What is the radius of the base in centimeters.
把一个高30厘米的圆柱底面平均分成若干个扇形，然后把圆柱切开，拼成一个与它等底等高的近似长方体，长方体的表面积比原来圆柱的表面积增加了180平方厘米，原来圆柱的底面半径是多少厘米．
<gadget id="calculator">180 / 2 / 30</gadget>
<output>3</output>

<result>3</result>