If \(A = \left[ {\matrix{ 1 & 2 \cr a & b \cr } } \right]\) & the product of A and its transpose is \( \left[ {\matrix{ 5 & 0 \cr 0 & 1 \cr } } \right]\) then value of a & b is respectively is
1
\({2 \over {\sqrt 5 }},{3 \over {\sqrt 5 }}\)
2
\({{ - 2} \over {\sqrt 5 }},{{ - 3} \over {\sqrt 5 }}\)
3
\({2 \over {\sqrt 5 }},{{ - 1} \over {\sqrt 5 }}\)
4
\({1 \over {\sqrt 5 }},{2 \over {\sqrt 5 }}\)