6. Find the distance

John enters the circular bridge through exit A and wishes to leave through exit B. If John chooses to reach the exit B by taking the road connecting the two parallel roads, find the distance between the two parallel. Given, the length of the parallel roads are 24 $km$ and the distance between the point $D$ on the diagonal road to the central pole $P$ is 15 $km$.

 

 

Answer:

 

The distance between the two parallel roads is  $km$.