Magnetic flux through a closed loop will be given by formula

here
B = magnetic field
A = area
= angle between normal to plane and magnetic field
Now we will use here the above formula for all the given conditions
i) magnetic field is normal to the plane
magnetic flux = BAcos0


ii) magnetic field makes 30 degree with normal to the plane
magnetic flux = BAcos30


iii) magnetic field is perpendicular to the normal of the plane
magnetic flux = BAcos90

