A minimum because the function is positive. Positive quadratic functions always concave upwards (in a “bowl-like” shape), creating a curve/minimum at the bottom.
With a uniform electric field, flux go along parallel paths, then flux is therefore proportional to the cosine of the angle rotated.
0 degree rotation => cos(0)=1 => 100% of flux.
60 degrees rotation => cos(60) => 0.5 => how many % of flux?
You just have to multiply straight across. Multiply the numerators for the new numerator, and the denominators for the new denominator.
5*3=15
4*8=32
15/32 is the answer (b).
