Random walk in the plane

A particles moves in $\mathbb{R^2}$ started at the origin. At each stage $i (i = 1, 2, …)$, the particles would move, independently of all the stages before, one of the four directions North, East, South and West 1 unit, with probability $1 \over 4 $ each.Let $T_n$ be the distance from the origin just after $n$ steps. What is $E(T_n)$. I tried define 4 $1\times 2$matrice with only $1,0,-1$ in all entries. The use technique similar to simple random walk in 1 dimension and we know that for a $1\times 2$ matrice $(x,y)$, the distance from origin =$\sqrt {x^2+y^2}$ but i am not sure how to like the 1 D to 2 D. As in 2 D there are 4 possible direction.

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