3. Consider the vector function $$ overrightarrow[r(t)}=\frac{t^{2}-1}{-1} \vec[\imath}+\sqrt{t+8} \vec[\jmath}+\frac{\sin (\pi t)} {\ln t} \vec[k] $$ (a) Find the domain of the vector function. (b) Find $\lim _{t ightarrow 1} \overrightarrow r(t)}$ SP.SD. 428