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Outside the circular musical fountain with a radius of12m, there is a circular viewing platform with a width of 8m. What is the area of this circular observation deck?
Because the circular viewing platform is 8 meters wide, the radius of the great circle formed by the music fountain and the viewing platform is R= 12+8=20.
So the area of this great circle is: s (large) = π r 2 = 400 π.
The area of circular music fountain is: s (small) = π r 2 = 144π.
Therefore, the area of the circular observation deck is: S=S (large) -S (small) =256π.