We studied the interplay of the biaxial and the uniaxial contributions to the in-plane magnetic anisotropy of (Ga,Mn)As epilayers through comprehensive dc and ac magnetic susceptibility measurements. Detailed information about the magnetic anisotropy was obtained from hysteresis curves recorded for various crystal orientations and from the temperature dependence of the magnetization. The measured orientations were the [110], [−110], and [100] directions. Ac susceptibility measurements were also conducted for these directions. We argue that the peaks in the real and the imaginary parts of the ac susceptibility cannot be explained within the single-domain spinreorientation model.