"the figure below shows a triangular wooden frame abc. the side ad of the frame has rotted and needs to be replaced:

triangle abc has length of bc equal to 16 inches. a line segment dc joins the point d on ab with point c. measure of angle abc is 90 degrees, acd is 15 degrees and measure of angle dcb is 30 degrees.

what is the length of the wood that is needed to replace ad? "

6.8 inches
6.2 inches
3.2 inches
2.8 inches