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#1 2012-12-09 09:13:24
- zee-f
- Member
- Registered: 2011-05-12
- Posts: 1,220
Transformations
Hi,
I am really stuck on how to rotate the following
Rotate the triangle 270 clockwise around (0,0).
One, who adopts patience, will never be deprived of success though it may take a long time to reach him. Imam ali (as)<3
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#2 2012-12-09 09:44:56
- Bob
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- Registered: 2010-06-20
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Re: Transformations
hi zee-f
When you rotate 270 clockwise, that's the same as 90 anticlockwise. (90, 180, 270, 360)
Look at the point (2,1) I've boxed it into a rectangle and then showed the whole rectangle rotating.
That corner moves to (-1,2) For 90 degrees that sort of thing always happens. The x and y coordinates swap over and one becomes negative.
It happens because the across distance in the rectangle becomes the up distance and the up becomes the across (but now going to the left ... ie. it is now a negative amount).
2 ----> -1
1 ----> 2
So you should be able to do the other points the same way.
Bob
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 
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#3 2012-12-10 03:26:16
- zee-f
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- Registered: 2011-05-12
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Re: Transformations
I rotated the paper 270 clock wise so 3 times clockwise and I got
One, who adopts patience, will never be deprived of success though it may take a long time to reach him. Imam ali (as)<3
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#4 2012-12-10 06:27:12
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Transformations
Hi zee-f;
That is correct!
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#5 2012-12-10 06:27:37
- Bob
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- Registered: 2010-06-20
- Posts: 10,621
Re: Transformations
hi zee-f,
That looks good to me,
Bob
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
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#6 2012-12-10 08:18:03
- zee-f
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- Registered: 2011-05-12
- Posts: 1,220
Re: Transformations
I choose B and it was incorrect but why doesn't the angle change because the size is getting bigger.
1. An angle changes in size as it undergoes a dilation.
A False
BTrue
One, who adopts patience, will never be deprived of success though it may take a long time to reach him. Imam ali (as)<3
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#7 2012-12-10 08:28:22
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Transformations
Hi;
The sides are dilated by a common factor but the ratios of the sides remain the same. In plain english the triangle will look the same just bigger.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#8 2012-12-10 10:21:47
- Bob
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- Registered: 2010-06-20
- Posts: 10,621
Re: Transformations
hi zee-f
I call it an enlargement but it is the same as a dilation.
I made a triangle ABC.
Then I made it bigger = DBE
The angles stay the same.
Bob
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
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