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# re-post

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This question was already answered but i did'nt understand. please check my post and give me a better explaination:)

From a point P on the ground the angle of elevation of the top of a tower is 30°and tht of the top of a flagstaff fixed on top of the tower is 60°. If the length of the flagstaff is 5m, find the height of tower.

SARAHann  Mar 12, 2017

### Best Answer

#3
+12691
+10

From the diagram, x= tower height

tan 30 = x / d

tan 60 = (x+5)/d      re arrange   d= (x+5)/tan60 = .57735x + 2.8868    Substtitute this into the first equation

tan30 = .57735 = x/(.57735x+2.8868)  solve for x

.33333x +1.6666=  x

x= 2.5 m 'tower' height    (short !)

ElectricPavlov  Mar 12, 2017
#1
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Hi Sarah,

Do you have the address of your original question so that we can go to it?

(do you know what I mean? - just copy the address and paste it into a new post here)

It is good that you say when you do not understand but it is important that you say it on the original thread because the answerer want your feedback.

People often give trivial anwers because they do not think anyone is really trying to learn from it.  We get so little feedback here.  Many askers only want to copy the answer and do not really want to learn.

Anyway, if you have that original question can you please copy the address and post it in here and then I will help you some more. :)

Melody  Mar 12, 2017
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Here's the weblink Melody

- http://web2.0calc.com/questions/applications-of-trigonometry

I did say in my original 1 tht i did'nt understand. But no one answered. Could u check my feedback in the org one? I hv said wut i did'nt understand based on CPhil's answers. Thanks a lot!

SARAHann  Mar 12, 2017
#2
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I found all these ones, that CPhill answered,  but the one you are asking now does not seem to be there.

http://web2.0calc.com/questions/applications-to-trignometry_1

Melody  Mar 12, 2017
#3
+12691
+10
Best Answer

From the diagram, x= tower height

tan 30 = x / d

tan 60 = (x+5)/d      re arrange   d= (x+5)/tan60 = .57735x + 2.8868    Substtitute this into the first equation

tan30 = .57735 = x/(.57735x+2.8868)  solve for x

.33333x +1.6666=  x

x= 2.5 m 'tower' height    (short !)

ElectricPavlov  Mar 12, 2017
#5
+93303
+10

Hi again Sara, thank you for giving me what I asked for.  I can see that you did ask for more help before too, just like you said :)

It is very easy for things like this to be overlooked so it was good that you reposted.  :)

You have lots of answers now but if it is still not clear to you then say so.  :))

If you would like me, or someone else to look at it specifically for you, you can also message us privately, don't forget to include the address as well though so we can find it :)

If you have specific questions about someone's answer then aks them on the forum and maybe back it up with a private message :)

Melody  Mar 13, 2017
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+302
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Hey, melody! thank you for helping me. I understood how to solve the question when my doubt was cleared. I had made a mistake while I was working out the problem. thank you so much for looking out for me!

cheers!

SARAHann  Mar 15, 2017

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