  Measurements of black hole spin made using the continuum-fitting method rely
on the assumption that the inclination of the black hole's spin axis to our
line of sight is the same as the orbital inclination angle of the host binary
system. The X=ray and radio jet data available for the microquasar XTE
J1550-564 offer a rare opportunity to test this assumption. Following the work
of others, we have modeled these data and thereby determined the inclination
angle of the jet axis, which is presumed to be aligned with the black hole's
spin axis. We find a jet inclination angle of approximately 71 degrees and
place an upper limit on the difference between the spin and orbital
inclinations of < 12 degrees (90% confidence). Our measurement tests for
misalignment along the line of sight while providing no constraint
perpendicular to this plane. Our constraint on the misalignment angle supports
the prediction that the spinning black hole in XTE J1550-564 has aligned itself
with the orbital plane and provides support for the measurement of its spin via
the continuum-fitting method. Our conclusions are based on a simple and
reasonable model of a pair of symmetric jets propagating into a low density
cavity whose western wall is approximately 20% closer to XTE J1550-564 than its
eastern wall.
