CPM Homework Help : INT3 Problem 5-73

Rotated square, with horizontal & vertical diagonals. Second square, rotated the same, has left vertex at center of first square, and right vertex of first square is at center of right square. the overlapping sections are shaded. Two congruent overlapping squares are shown at right. If a point inside the figure is chosen at random, what is the probability that it is not in the shaded region?

Hint:

2 overlapping squares, from problem figure, has additional segments as follows: in center shaded square, from left vertex to right vertex. In each square, from each center, 1 segment to the center of each side, creating 8 triangles in each square, with 2 triangles overlapping.

Answer:

$\frac{6}{7}$