The figure shows that the sector with 90 degrees of central angles centering on the point O and with radii 2, 4, 6, 8, 10 and 12 cm are drawn and in addition it is connected that the points having divided the arc AB (curving line of the sector) into six equally and the center O by a straight line.
Find the total area of the shadow portion about the figure of (1) and (2), respectively.