The equation of the circle is (x-cosa) ^ 2 + (y-sina) ^ 2 = 1 / 2. When a changes from 0 to 2 π, the area swept by the moving circle is 3Q .

The equation of the circle is (x-cosa) ^ 2 + (y-sina) ^ 2 = 1 / 2. When a changes from 0 to 2 π, the area swept by the moving circle is 3Q .

The area swept by the moving circle is a ring, the radius of outer ring is 1 + √ 2 / 2, the radius of inner ring is 1 - √ 2 / 2, area = π * [(1 + √ 2 / 2) ^ 2 - (1 - √ 2 / 2) ^ 2] = 2 √ 2 π