Equation Icon  [ ] a ( a)2 a b 3 gtt = − 1 + 2aayˆ + aayˆ + ℰabˆy ˆy + O (s ) , (9.24 ) 2 gta = − --𝜀abcℬbdyˆcˆyd + O (s3), (9.25 ) 3( c d) 3 gab = δab 1 − ℰcdˆy ˆy + O (s ). (9.26 )