Two poles are x m A.

B.

C.

D.

Let the height of the poles be h and 2h respectively.

Let the angles of elevation of the top of the poles from the midpoint M of the line joining the feet of the poles be α and ß.

Also, given that they are complementary angles, α + ß = 90⁰

From the figure we see that,

and

and

Now,

tan (90 – α) = 2 tan α

cot α = 2 tan α

Now,

The height of the shorter pole is .