What is an envelope?

[Bridgeport]

Where can I found more about envelopes?

http://en.wikipedia.org/wiki/Envelope_%28mathematics%29

Do you know why for the family of curves given parametrically (f(t,c),g(t,c)) the envelope is give by solution of the equation: $0= \frac{\partial f}{\partial t} \frac{\partial g}{\partial c}- \frac{\partial f}{\partial c} \frac{\partial g}{\partial t}$

http://mathworld.wolfram.com/Envelope.html

[Dan B-Yallay]

Couldn't find much info on this, except may be definitions on Russian. What is it about?
And how did you get into Russian speaking resource?

[Freude]

A piece of cake! One can translation obtain clicking on the corresponding language in the left bottom of the page.

http://ru.wikipedia.org/wiki/%D0%9E%D0% ... 0%B0%D1%8F

If you have no the russian-language keyboard layout, you can use this emulator:

http://www.yandex.ru/keyboard_qwerty.html

Just type, copy and paste.

[NAT]

The envelopes are considered in the courses of differential geometry. But in modern books with this title they are often omitted. The case of implicitly given curve is considered in Rashevsky, Course of differential geometry (in Russian) and Pogorelov, Differential geometry (in Russian). You can find more in Favard, Cours de geometrie differentielle locale (in French, Russian translation is available). I know nothing about the English translations of these books. Can you read in Russian?

[Dan B-Yallay]

Freude писал(а):

A piece of cake! One can translation obtain clicking on the corresponding language in the left bottom of the page.

http://ru.wikipedia.org/wiki/%D0%9E%D0% ... 0%B0%D1%8F

If you have no the russian-language keyboard layout, you can use this emulator:

http://www.yandex.ru/keyboard_qwerty.html

Just type, copy and paste.

Это для кого ссылки?
Я спрашивал товарисча о том как он вообще сюда забрел без русского языка. Хотя вроде транслитом он по-русски пишет.

[нг]

1) Форум допускает использование английского языка.

2) Достаточно много людей владеют иностранными языками пассивно, например, читают, но не пишут, понимают, но не говорят. В качестве такового иностранного может выступать и русский.

3) Дискуссия о используемом Bridgeport языке — явный оффтоп, отношения к огибающей (envelope) не имеющий.

[Bridgeport]

Y izvinyus' za offtop! Prosto dly proysneniy! Y russkiy (no vremenno ne v Rossii)! Prosto klaviaturi u meny russkoy net. Pisat' cherez paste and copy i Yandex medlenno, tak chto rasschitivau na vashe ponimanie! Vse ravno moi soobsheniy soderjat prostoy angliskiy da i neochen' mnogo!

Spasibo za otveti i poysneniy.

[нг]

Bridgeport
Правила не разрешают использования транслитерации. Вам может помочь, например, http://translit.ru