Posted by Rose on Saturday, March 9, 2013 at 4:00pm.
I looked at your diagram and noticed that you sketched a line from D to AB
That was good, now let the point of contact be E
so clearly triangle ADE is right-angled
with AE = 9 and DE = 23
by Pythagoras:
AD^2 = 9^2 + 23^2 = 610
AD = √610 = appr 24.7