Math Is Fun Forum

samuel.bradley.99

Member

Registered: 2016-03-16

Posts: 51

Change of shape

How can we transform a parallelogram with sides n and 1.1*n into a rhombus of equal area, just by one cut?

Last edited by samuel.bradley.99 (2016-10-14 06:21:56)

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Change of shape

Hi;

Equal surface? What does that mean?

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zetafunc

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Re: Change of shape

Maybe he means equal area.

samuel.bradley.99

Member

Registered: 2016-03-16

Posts: 51

Re: Change of shape

Exactly, I corrected the wording. Sorry guys but English is not my mother tongue!!

Maybe he means equal area.

thickhead

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Registered: 2016-04-16

Posts: 1,086

Re: Change of shape

Only in certain cases it can be done.If one of the diagonals has the dimension of a side either n or 1.1 n ,it can be cut along that diagonal and pasted on the other side.

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Bob

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Registered: 2010-06-20

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Re: Change of shape

hi samuel.bradley.99

This works only if A lies on that circle.  Still working on a general case.

AB = DC = 1.1n

AD = BC = n

Note AC = n, so the dotted diagonal will make the cut.  Translate ADC (ie. Move it maintaining the parallel directions)  so that DC fits over AB as the new diagonal. 

The new parallelogram has four equal sides of size n, so it is a rhombus.

Bob

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samuel.bradley.99

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Registered: 2016-03-16

Posts: 51

Re: Change of shape

Thank you, but how about in the general case, where we don't know whether A lies on the circle?

Bob

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Registered: 2010-06-20

Posts: 10,608

Re: Change of shape

hi samuel.bradley.99

General solution:

Draw parallelogram ABCD where AB = 1.1n and BC = n

With centre D and radius 1.1n, draw an arc to cut AB at E.

The cut required is along the line DE.

Remove the triangle coloured yellow, and move it to the position shown in orange.

AB = DC = EF = FC = 1.1n so EFCD is the required rhombus.

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

samuel.bradley.99

Member

Registered: 2016-03-16

Posts: 51

Re: Change of shape

Guys you are geniuses! Respect!!
Thank you so much!!