In the following figure, \(WXYZ\) is a rhombus. Diagonals \(WY\) and \(XZ\) intersect at \(O\). \(A\) and \(B\) are mid-points of \(OW\) and \(OX\) respectively. If \(WY\) \(=\) 16 \(cm\) and \(XZ\) \(=\) 30 \(cm\), then \(AB\) is:
 
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The value of \(AB\) \(=\)  \(cm\)