(b)13 m
Let the poles be and CD
It is given that:
AB = 6 m and CD = 11 m
Let AC be 12 m
Draw a perpendicular farm Bon CD, meeting CD at E
Then,
BE = 12 m
We have to find BD.
Applying Pythagoras theorem in right-angled triangle BED, we have:
BD2 = BE2 + ED2
= 122 + 52 (∵ ED = CD − CE = 11 − 6)
= 144 + 25 = 169
BD = 13 m