  Forward shocks by radio jets, driven into the intracluster medium, are one of
the indicators that can be used to evaluate the power of the jet. Meanwhile
high-angular-resolution X-ray observations show the Mach numbers of powerful
radio jets are smaller compared to that of theoretical and numerical studies,
$\mathcal{M_{\rm obs}} < 2$. Our aim is to systematically investigate various
factors, such as projection effects and temperature non-equilibration between
protons and electrons, that influence the Mach number estimate in a powerful
jet. Using two-temperature magnetohydrodynamic simulation data for the Cygnus A
radio jets, whose Mach number is approximately 6, we construct mock X-ray maps
of simulated jets from various viewing angles. Further, we evaluate the shock
Mach number from density/temperature jump using the same method of X-ray
observations. Our results demonstrate that measurements from density jump
significantly underestimate the Mach numbers, $\mathcal{M} < 2$, around the jet
head at a low viewing angle, $\lessapprox 50^{\circ}$. The observed post-shock
temperature is strongly reduced by the projection effect, as our jet is in the
cluster center where the gas density is high. On the other hand, the
temperature jump is almost unity, even if thermal electrons are in instant
equilibration with protons. Upon comparison, we find that shock property of our
model at viewing angle of $<$ $55^{\circ}$ is in a good agreement with that of
Cygnus A observations.
