Question

An observer standing at distance of 72 m from a building measure the angle of elevation of the top and foot of a flagstaff on the building as 54 degree and 50 degree. find the height of the Flagstaff.
$( \tan54 = 1.376) ( \tan(50 = 1.192)$
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Answer 1

Answer

From the ΔABC,

tanθ=

BC

AB

tan54

∘

=

72

AB

AB=1.376×72=99.07

From the ΔDBC,

tanα=

BC

DB

tan50

∘

=

72

DB

DB=1.192×72=85.82

Now, the length of the flagstaff = AB - DB

=99.07−85.82

=13.25

Therefore, the length of the flagstaff is 13.25m.