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**niharika_kumar****Member**- From: Numeraland
- Registered: 2013-02-12
- Posts: 1,034

1.what is a rectangular parallelopipe?

2. what is the ratios of areas of incircle and circumcircle of an isosceles right angled triangle?

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,744

hi Niharika

(i) Sounds like just another name for a cuboid:

http://en.wikipedia.org/wiki/Parallelepiped

Look at the special cases section.

(ii) Working on it.

LATER EDIT: (diagram in next post)

In my diagram the radius of the circumcircle is AF. If you let AC = CB = a then you can get an expression for the area in terms of a.

G is the centre of the incircle so its radius is BFtan(22.5) So you can get an expression for its area in terms of a.

As both will have a^2 this will cancel when you divide one by the other.

I've done that by measurement on my diagram and it doesn't appear to be any simple value.

Bob

*Last edited by bob bundy (2014-01-31 20:45:19)*

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,744

diagram here

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

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