Analyses of $D^+\to K_S^0 K^+$ and $D^+\to K_S^0 π^+$

Using data collected with the CLEO II detector at the Cornell Electron Storage Ring, we present new measurements of the branching fractions for $D^+ \to K_S K^+$ and $D^+ \to K_S \pi^+$. These results are combined with other CLEO measurements to extract the ratios of isospin amplitudes and phase shifts for $D \to KK$ and $D \to K\pi$.