A body of mass 6kg rests on an inclined plane. The normal reaction is R and the limiting frictional force is F as shown in the image above. if F = 30N, and g = 10ms2 then the angle of inclination ( theta ) is
-
A.
( 15^{circ} ) -
B.
( 30^{circ} ) -
C.
( 45^{circ} ) -
D.
( 60^{circ} ) -
E.
( 75^{circ} )