Question

A square is inscribed in the circle. A point in the figure is selected at random. Find the probability that the point will be in the part that is NOT shaded.

Answer 1

Ok 
Probability (the point will be on unshaded part)  = area of unshaded part / area of the circle.

=   pi r^2 - s^2
     --------------            where r = radius of circle and s = length of the side of the square.
        pi r^2