$27\mathrm{.}9$ A circular area with a radius of $6\mathrm{.}50$ cm lies in the xy@plane. What is the magnitude of the magnetic flux through this circle due to a uniform magnetic field B $=0\mathrm{.}230$ T $($a$)$ in the $+$z$-$direction; $($b$)$ at an angle of $53\mathrm{.}1$ from the $+$z$-$direction; $($c$)$ in the $+$y$-$direction?