Q.

A vertical pole of length 6 m casts a shadow 4 m long on the ground and at the same time a tower casts a shadow 28 m long. What is the height of the tower?

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a

25m

b

44m

c

35m

d

42m  

answer is D.

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Detailed Solution

Given that, a vertical pole of length 6 m casts a shadow 4 m long on the ground and at the same time a tower casts a shadow 28 m long.
Let CD be a pole of length 6 meter,
DF = 4 m be the length of its shadow.
Let another tower AB cast shadow BE of length 28 m.
Question ImageThe sun will make equal angles with both the towers at same time.
DCF=BAE   ……[1]
The poles are upright, so angle with ground is right angle.
CDF=ABE   ……[2]
From [1] and [2], By AA similarity Criteria,
ΔCDF~ΔABE   We know that if two triangles are similar then their corresponding sides are in proportion and the corresponding angles are equal.
CD AB = DF BE   Putting values on the equation, we get
6 AB = 4 28 AB= 28 4 ×6 AB=42m  
Hence, the height of the tower is 42m.
Therefore, the correct option is 4.
 
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