the answer is 13. 90 if you round it to the nearest tenth. the nearest tenth is the 9 the first nine.( if the number is 0-5 then it will become a 0 but if the number is 5-9 you would add one to the number in front of it) since the number is 9 then the 8 would become a 9 so your answer would be 13.90
hope I explained it well enough.
AC and BD are perpendicular bisectors of each other.
=> ABCD is rhombus.
AD = 13
AE = √(13^2 - 12^2) = 5