Let T be a linear transformation from R^2 to R^2. and T is represented by the matrix B=
[(1/5)^(1/2) -2(1/5)^(1/2)]
[2(1/5)^(1/2) (1/5)^(1/2)]
with respect to the stantard basis of R^2.

a) Is T isometry?
b) does R^2 have an orthonormal basis for eigenvectors of T?

i can do a) but need help on b). i dont really understand what it is asking. is it asking to find an orthonormal basis for eigen space of T?