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## Discussion of Problem 1722. Observation Deck

What we must to find ?
Posted by Alias aka Alexander Prudaev 17 Oct 2009 22:52
I do not understand why, but my program gives
different result, than sample.

in this picture, i draw a figure with yellow,
i think area of this figure is an answer, i am right ?
http://slil.ru/28091271
Re: What we must to find ?
Posted by svr 17 Oct 2009 23:21
Question is simple.
H is not diven then we have plane problem.
Two adjacent, rejion after antey+ antey itself.
No subject
Posted by Alias aka Alexander Prudaev 18 Oct 2009 00:40
i do not understand you
Re: What we must to find ?
Posted by melkiy 18 Oct 2009 01:44
You filled with yellow only the area behind the new building. But the big inner circle must be included in "non-seen" region as well.
Re: What we must to find ?
Posted by Oleg Strekalovsky aka OSt [Vologda SPU] 18 Oct 2009 16:16
I think, that this problem can be solved only via integrals.
Analytic geometry doesn't work. I am right?
Re: What we must to find ?
Posted by svr 18 Oct 2009 16:25
No!i tried to use integral during contest: WA8- rounding error.
At the next day I found simple analytic solution.
Re: What we must to find ?
Posted by Oleg Strekalovsky aka OSt [Vologda SPU] 18 Oct 2009 17:02
Are you sure, that it is simple solution? =)
A think, that main problem is that we can't make any Circle Sector, except sector from the center of town, so we can't find exact area behind New Antey Building. Areas of figures with rounded border are hardly calculated.
Re: What we must to find ?
Posted by svr 18 Oct 2009 17:14
The figure can be decomposed into triangles and
circle segments. All lengths and , therefore areas
are easy calculated, typical school problem.

Edited by author 18.10.2009 17:15
Re: What we must to find ?
Posted by Oleg Strekalovsky aka OSt [Vologda SPU] 20 Oct 2009 13:18
Solution on Java exists!
No problems with accuracy of calculating.
Re: What we must to find ?
Posted by uzairBaig 24 Apr 2010 17:17
the link for the diagram has expired
can anyone draw a figure and upload again, the area to find out is unclear to refer to from the question.
Re: What we must to find ?
Posted by ASK 11 Apr 2018 19:21
The new tower blocks its own area plus all the town behind it. This sum needs to be divided by (pi * R**2) and multiplied by 100.