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 ?
download this picture:
http://slil.ru/28091271

Question is simple.
H is not diven then we have plane problem.
Two adjacent, rejion after antey+ antey itself.

i do not understand you

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.

I think, that this problem can be solved only via integrals.
Analytic geometry doesn't work. I am right?

No!i tried to use integral during contest: WA8- rounding error.
At the next day I found simple analytic solution.

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.

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

Solution on Java exists!
No problems with accuracy of calculating.

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.

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.