Find the 2 by 2 matrix representing the transformation which maps triangle A onto triangle B.

I need, not just the solution but the method to it, pretty quickly. Appreciate any help you offer me, thanks!

As far as I can tell, it's a anti-clockwise 90 degree rotation. So would I work it out by...

1. Select the points (1,0) and (0,1) on the graph, and then the matrix is

(1 0

(0 1)

2. Find the images of these points under rotation

3. Write the position vectors of these images.

4. The position vector of the image of the first point becomes the first column.

5. The position vector of the image of the second point is the second column of the required matrix.

So then my answer is

(1 0)

(0-1) ?