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HSC Stuff => HSC Maths Stuff => HSC Subjects + Help => HSC Mathematics Advanced => Topic started by: Albertenouttaten on July 24, 2021, 01:02:09 pm

Title: Help with angles of elevation and depression question
Post by: Albertenouttaten on July 24, 2021, 01:02:09 pm

Hi,

The terminology in this question is confusing me a bit. I get an answer of 18.5m but the answer has it has something else. Am I doing this question wrong?

Any help would be appreciated!

Title: Re: Help with angles of elevation and depression question
Post by: fun_jirachi on July 24, 2021, 01:14:56 pm

If you haven't already drawn an accurate diagram, do that. You should have a building of height \(h\), on top of which is a flagpole of height \(f\) (h, f are arbitrary choices), then from a point 250m away, lines to the base and top of the flagpole annotated with the correct angles.

You should then be able to deduce two equations from your diagram:
\[h = 250\tan (38) \\ h+f = 250\tan(40)\]

All you have to do now is solve for \(f\).

Title: Re: Help with angles of elevation and depression question
Post by: Albertenouttaten on July 24, 2021, 01:20:59 pm

Ahh okay I see where my confusion is. I thought '250 m from the base of the building' was referring to the base of the flagpole being 250 m VERTICALLY away from the base of the building. All good - makes sense now. Thanks!