# Thread: Transformation matrix (one triangle to another).

1. ## Transformation matrix (one triangle to another).

Hello,
I have made this account purely to find the way to answer this question, I have asked my maths teacher and he couldn't answer, so please can anyone answer it to me? thank you

The question I need to answer is the (b) section, please show me the working and explain it like you would to a five year old....

according to the mark scheme, the answer is:

0 -1
-1 0

and

1 0
0 2

(the answers are matrices)
please answer asap, I have attached the question
thanks

2. Hint for (b) (i):

Notice that the transformation f which maps T onto S is a symmetry with respect to r : x + y = 0 .

Try (b) (ii).

3. thanks for replying :-) , but I don't understand, do you mean T onto R? and how does that help me to find the required 2 by 2 matrix to map the triangle.
in the mark scheme it said that I would get one mark for showing simutaneous equations, but I have no idea what simutaneous equations have to do with the question...... can you please tell me the method to find the matrix? thanks

4. For T -> R, it is clear from the diagram that (x,y) -> (-y,-x).
What matrix does that?

5. thats a good method! thanks.
so, just a recab (please correct me if I am wrong)
x and y are switched and they both become into negatives, and to do that the matrix :

0 -1
-1 0

is used, ok, now I have an idea how to solve these kind of questions, but in other occasions, it is harder to guess the matrix, in b(ii), for example, point (-6, 2) became ( -6, 4) , so x remains the same and y is doubled, but how do I guess the matrix now?
thanks

6. Originally Posted by IBstudent
do you mean T onto R?

Right, it was a typo.