  We observed broken-symmetry quantum Hall effects and level crossings between
spin- and valley- resolved Landau levels (LLs) in Bernal stacked trilayer
graphene. When the magnetic field was tilted with respect to sample normal from
$0^{\circ}$ to $66^\circ$, the LL crossings formed at intersections of zeroth
and second LLs from monolayer-graphene-like and bilayer-graphene-like subbands,
respectively, exhibited a sequence of transitions. The results indicate the LLs
from different subbands are coupled by in-plane magnetic fields
($B_{\parallel}$), which was explained by developing the tight-binding model
Hamiltonian of trilayer graphene under $B_{\parallel}$.
