The Chinese knot is a unique hand-woven handicraft of the Han nationality. The taste and wisdom shown on it are just one aspect of the ancient civilization of the Han nationality. A Chinese knot in the shape of an isosceles triangle has a circumference of 23 cm. If the length of the base is 7 cm, what is its waist length?
中国结是一种汉族特有的手工编工艺品，它身上所示的情趣与智慧正是汉族古老文明中的一个侧面．一个等腰三角形形状的中国结，周长是23cm，如果底边长是7cm，它的腰长是多少？
<gadget id="calculator">23 - 7</gadget>
<output>16</output>

<gadget id="calculator">16 / 2</gadget>
<output>8</output>

<result>8</result>