Insert a 12 cm long lower wooden stick vertically into a cylindrical cup filled with water (the cup is placed flat on the table), mark the mark A on the watermark (the place where the sleeper is in contact with the wooden stick), and then insert the small wooden stick Turn the stick upside down, do it again according to this method, and mark the mark on the watermark B. If the length of AB is 2 cm, what is the depth of water in the cup?
将一根长12厘米的下木棒垂直插入一个只盛有水的圆柱形水杯(水杯平放在桌面上)，在水印处(睡眠与木棒接触的地方)标上记号A，再将小木棒倒过来，依照其按此方法再做一次，在在水印处标上记号B．如果AB的长度是2厘米，那么杯内水深是多少厘米？
<gadget id="calculator">12 + 2</gadget>
<output>14</output>

<gadget id="calculator">14 / 2</gadget>
<output>7</output>

<result>7</result>