question_answer

Two poles 15 metres and 30 metres high stand upright in a playground. If their feet be 36 metres apart, find the distance between their tops.

A) 36 m

B) 39 m

C) 15 m

D) 30 m

E) None of these

Correct Answer: B

Solution :

Explanation Option (b) is correct. Let AL, BM be poles with tops at L and M resp. LA = 15m, MB = 30 m, AB = 36 m. Let LN be parallel to the ground             LN = AB = 36 m And      MN = 30 - 15                         = 15 m \[\therefore \,\,\,\,LM=\sqrt{{{36}^{2}}-{{15}^{2}}}\]              \[=\sqrt{1296+225}=39\,m.\]