Square ABCD has sides of length 1. Arc AC is an arc of the circle of radius 1 centered at B. Arc BD is an arc of the circle of radius 1 centered at A. These arcs divide the square into four regions, $$S_1, S_2, S_3$$, and $$S_4$$.
Quantity A
The area of region $$S_1$$ minus the area of region $$S_3$$
Quantity B
$$\frac{π}{2}-1$$