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Joint Entrance Examination
Mathematics
Straight Lines and Pair of Straight Lines
Question 213
Question 213 of 303
Easy
MCQ
If two vertical poles 20m and 80m high stand apart on a horizontal plane, then the height (in m) of the point of intersection of the lines joining the top of each pole to the foot of other is:
A
16
B
18
C
50
D
15
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Official solution
Standard result:
h
1
h
2
h
1
+
h
2
=
20
×
80
100
=
16
\dfrac{h_1h_2}{h_1+h_2} = \dfrac{20\times80}{100}=16
h
1
+
h
2
h
1
h
2
=
100
20
×
80
=
16
m.
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