Answer
$1$
Work Step by Step
$s$ = $rθ$
$sin{\frac{θ}{2}}$ = $\frac{\frac{d}{2}}{r}$
$d$ = $2r{sin{\frac{θ}{2}}}$
$\lim\limits_{θ \to 0^{+}}{\frac{s}{d}}$ = $\lim\limits_{θ \to 0^{+}}{\frac{rθ}{2r{sin{\frac{θ}{2}}}}}$ = $\lim\limits_{θ \to 0}{\frac{\frac{θ}{2}}{{sin{\frac{θ}{2}}}}}$ = $1$
