2. Find the unknown part of the triangle

 

\(\triangle ABC\) and \(\triangle APQ\) satisfy the SSS similarity criterion. \(AP\), if \(AQ\) \(=\) \(4\) \(cm\) and \(QC\) \(=\) \(16\) \(cm\). Also, \(AB\) \(=\) 21.5 \(cm\) and \(AC\) \(=\) 20 \(cm\) then \(AP\) is __________ \(cm\)