The functions that have graphs that oscillate (i.e., graphs that repeat their values in a periodic manner) are:
- \( y = \sin \theta \)
- \( y = \cos \theta \)
The other functions, \( y = \tan \theta \), \( y = \sec \theta \), \( y = \csc \theta \), and \( y = \cot \theta \), do not oscillate in the same way as sine and cosine; instead, they have asymptotic behavior (approaching infinity) at certain points.
So the correct responses are:
- \( y = \sin \theta \)
- \( y = \cos \theta \)