Transverse e is BC vertical line.
EH:GH= 1:2 can be easily obtained from similarity.
(Shadow length: rod length = 2: 1)
And because ∠ ech = 30 and CE=2EH.
CE=4M
EH=2M
Similarly, CH=2√3M, GH=2√3M.
(CE:CH= 1:(√3)/2)
BG=4+2x√3/2=4+√3