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 Discussion: All Topics Topic: Proof of Pythagoras Theorem

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 Subject: RE: Proof of Pythagoras Theorem Author: NateB Date: Apr 2 2008
For your first question, I recommend using the 'movement' buttons rather than
the animation buttons.  You can tell a point to move to a different point and it
stays there.  I usually make a few buttons and control the movement as a
presentation.

As far as the object disappearing and being replaced by a differently defined
but visually identical object, you can make a presentation that moves A and
hides A and shows B.  This allows you to introduce independent points part way
through a complicated construction and they have the freedom of independence
without the arbitrary location.  I have used this technique on a Stats sketch to
show points apparently moving through two tranformations, although you really
see a couple of different sets of points.  The file and others can be found on

Finally, you can make a point go around a corner by using the movement buttons.
If you want point A to go along a straight line to point B where it will change
directions and continue to point C, create two buttons: Move A-->B and Move
A-->C.  Now make a presentation of the buttons and as long as the movements
happen sequentially (not simultaneously) then the visual effect will be what you
are describing.

You can create a point on a polygon.  Click (in order) the points that define a
polygon.  Construct a polygon interior.  With the polygon selected, Construct a
point on the polygon.  This point can be told to go to a different point on the
polygon, and it seems to take the shortest route.

Hope this helps.

Nate

On Apr  1 2008, Davem wrote:
> I once saw a proof of Pythagoras' Theorem created with Cabri
> Geometry which involved shears and translations.  I'm trying to
> setup a similar demonstration in Sketchpad, but I'm meeting a few
> stumbling blocks and wonder if anyone can help.

1)  Sometimes I
> want to use an animation button to move a point (and hence an
> object, e.g. a square) along a line, and then have it stop at the
> end.  But in GSP it always returns to its starting point at the end
> of the animation.  Anyway to overcome this/work around this?

2)
> I'd like to make an object disappear then have another (apparently)
> identical object reappear in the same place.  At present the change
> is very obvious.  Any suggestions how to deal with this?

3)  Is
> there anyway I can make a point go around a corner?  I'm remembering
> that in Cabri I could define a point as being on the sides of a
> polygon, but is there anyway to achieve this in Sketchpad?

Those
> are the main stumbling blocks I'm up against at present.  Any help
> would be much appreciated.