Find the fluid force on a circular observation window of radius 1 foot in a vertical wall of a large water-filled tank at a fish hatchery when the center of the window is 

(a) 3 feet and 

(b) d feet
(d > 1) below the water's
surface (see figure). Use
trigonometric substitution
to evaluate the one integral.
Water weighs 62.4 pounds
per cubic foot. (Recall that
in a similar
problem, you evaluated one
integral by a geometric formula
and the other by observing that
the integrand was odd.)

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