The side of the square = X. Therefore the radius of the circle = 2^(1/2)*X/2. The shaded area = 1/4*(area of the circle - area of the square) = 1/4 * (pai *X^2/2 - X^2)
1) 一个r与X的关系. If r is the radius, this info is useless. Insufficient. 2) the area of the shaded area. Sufficient.
Answer is B (if r is radius and condition 1 only gives a relationship instead of hard value.)
1) 一个r与X的关系. If r is the radius, this info is useless. Insufficient.
quesion: if there's a relationship between r and x as given in 1), which means an equation there; therefore, we already have another equation: x=2^1/2r; from the two equations, we can get the real numbers of x and r, so 1) do solve the problem and as a result it's sufficient.