2.
M must be (0,0) since it coincides with the origin
R must be (a+b, √(a²-b²)).
The x-coordinate is b from A translated to the right by a.
The y-coordinate is the same as A.
(I think the square root is there to confuse you).
3.
R(0,0)
C(a,b) (same x as T, same Y as E)
5.
Not sure how to prove that.