Height & Distances

I think there's some error in the quest.

Consider a pole whose upper half (3l/4) subtends an angle θ and the lower half (l/4) subtends an angle α .

so you get the equations tan(α+θ) = l/40
and tan α = l/160

and you have been given that tan θ = 3/5

solving these you get a quadratic in l which gives you the answer.

The error is that the anser is coming -40 m . and -ve length is impossible.

By the way can u plzz provide the source ?

l =4 0 m

I got the ans after solving the eqn in ur method

U must have made some error