Magnetic flux is calculated as #Phi_B = B*A*costheta#

where #theta# is the angle between the direction of the field and the normal to the surface enclosed by the loop.

In this case, the field is 0.230 T, and the area is #A=pi*r^2= 0.0133 m^2#

(Note the necessary change from cm to m.)

So, if #theta# = 0°, as in part a of your question (If the circle lies in the #x-y# plane, the normal points perpendicular to the plane - in the direction of the z-axis.)

#Phi_B= (0.230*0.0133)*cos(0°)=0.00306# Wb (webers)

And in part b, where #theta#= 53.1°

#Phi_B= (0.230*0.0133)*cos(53.1°)=0.00184# Wb