Chiannelysnidn
Answered

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the angle of elevation of an unfinished tower from a point of 100m away from its base is 30°.if it will be raised by 20m what will be the new angle of elevation from the same point?​

Sagot :

Hannamontemayoridn

Answer:

Solution

Correct option is D)

Let PA be the unfinished tower.

Let B be the point of observation i.e. 120 m away from the base of the tower.

Now, AB = 120m

Let, ∠ABP=45°

Let h m be the height by which the unfinished tower be raised such that its angle of elevation of the top from the same point becomes 60°.

Let CA = h &∠ABC=60°

In triangle ABP,

tan45°=

AB

PA

⇒1=

120

PA

⇒PA=120M

Now, in triangle ABC,

tan60°=

AB

CA

3

=

120

120+h

h+120=120

3

h=120(

3

−1)

h=120(1.732−1)→(as

3

=1.732)

h=120×0.732

h=87.84m