The longitudinal and transverse magneto-optical Kerr effects have been used for understanding the magnetization processes in single crystal Fe/GaAs (100) thin films. By using both of these Kerr effects it is possible to concurrently detect two orthgonal in-plane magnetization components. Presented here are Kerr hysteresis curves for magnetic fields directed along the in-plane 100 and 110 directions of the Fe films. For the 100 direction the magnetization curves are square, while for the 110 unusual overshoots are present in the Kerr hysteresis curves. In order to understand the origin of these curves for the 110 direction, simulations were done using the Fresnel reflection coefficients for the in-plane Kerr effects and a coherent-rotation model for the magnetization process. There is good agreement between the simulated Kerr hysteresis curves and the experimental data. The overshoots along with the general analyzer dependence of the hysteresis curves are reproduced in the simulations. However, the magnitude of the reversal and saturation fields of the modeled loops cannot be brought into agreement with the data. For applied fields near the 110 directions, the analysis suggests that the reversal occurs through the nucleation and/or unpinning of 90°domains at two distinct transition fields followed by coherent rotation.