Question 846130
You messed up here
622.04=254.4690049+28.2733388(L)
622.04=282.7433388(L)

from here  you can get 
622.04=254.4690049+28.2733388(L)
L = 13.0006

using 3.14 for pi
622.04 = 3.14×81+3.14×9L
622.04 = 28.26L+254.34
367.7=28.26L
L = 13.0113