Ta có : \(CH=CH'=\dfrac{8}{2}=4\left(m\right)\)
\(tan35^o=\dfrac{AH}{CH}\Rightarrow AH=CH.tan35^o=4.0,7=2,8\left(m\right)\)
\(tan30^o=\dfrac{BH'}{CH'}\Rightarrow BH'=CH'.tan30^o=4.0,6=2,4\left(m\right)< AH=2,8\left(m\right)\)
Nên cột A cao hơn cột B là \(2,8-2,4=0,4\left(m\right)\)