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# Transformations and rotations Tweet

Maths and statistics discussion, revision, exam and homework help.

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1. Transformations and rotations
I was wondering, if I was doing a question where there is a rotation, is there a way for finding out at what point its rotated by?

For example:
from A to C

it shows that for all (atleast for the questions i've done) 180 degree rotations, if you join up the vertices it gives you the point at which it is rotated.#

however how would i do it for something like 90 degrees?

or 45?

is there a method/technique for these?

Thanks!
2. Re: Transformations and rotations
You perpendicular bisect the lines joining the vertices
3. Re: Transformations and rotations
(Original post by TenOfThem)
You perpendicular bisect the lines joining the vertices

Do you have an example or anything? not quite sure what you mean? :O
4. Re: Transformations and rotations
You join A to A' then you create the perpendicular bisector of that line

You join B to B' then you create the perpendicular bisector of that line

You join C to C' then you create the perpendicular bisector of that line

Where they meet is the centre of rotation
5. Re: Transformations and rotations
You can use Matrices for transformations/ rotations (and even a combination of them into one matrix).
6. Re: Transformations and rotations
(Original post by USB)
You can use Matrices for transformations/ rotations (and even a combination of them into one matrix).
at GCSE?
7. Re: Transformations and rotations
(Original post by TenOfThem)
at GCSE?
Yes, I'm doing GCSE and need to know (basic) Matrix transformations.

http://web.aqa.org.uk/qual/igcse/maths.php
8. Re: Transformations and rotations
(Original post by USB)
Yes, I'm doing GCSE and need to know (basic) Matrix transformations.

http://web.aqa.org.uk/qual/igcse/maths.php
that is the further maths gcse

I think it is unlikely that the op is doing that course

also it does not cover rotations about anything other than (0,0)
9. Re: Transformations and rotations
(Original post by TenOfThem)
that is the further maths gcse

I think it is unlikely that the op is doing that course

also it does not cover rotations about anything other than (0,0)
Hmm, but then the co-ordinates can be altered so it is as if the origin is the point of rotation.

Nevertheless the concept isn't difficult at this level at least, and is more rigorous than doing it by eye.
10. Re: Transformations and rotations
(Original post by TenOfThem)
You join A to A' then you create the perpendicular bisector of that line

You join B to B' then you create the perpendicular bisector of that line

You join C to C' then you create the perpendicular bisector of that line

Where they meet is the centre of rotation

Aaah right! Thanks ! +1