Answer:
A
Explanation:
DC / EC == EC / BC == 2 / 2*sqrt(5) == 2*sqrt(5) / BC
=> BC == 2*sqrt(5) * 2*sqrt(5) / 2 == 10
=> BD = BC - 2 = 8
DE = SQRT( 2*sqrt(5) * 2*sqrt(5) - 2*2 ) = sqrt(16) = 4
=> AD = 4+4 = 8
x = sqrt( AD*AD + BD*BD ) == sqrt( 8*8 + 8*8 ) ==sqrt( 2 )*sqrt(8*8) == 8*sqrt(2)
