Question 1208875
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A bowl with radius 30 cm , shaped like a hemisphere, is filled with water 
to two-thirds its depth. What is the surface area of the water, in cm²?
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The total depth of the bowl is the radius of 30 cm (given).
Two-thirds of the total depth is 2/3 of 30 cm, i.e. 20 cm.


Hence, 10 cm is over the water surface.


Thus the square of the radius of the water surface in the bowl is (from Pythagoras)

    r^2 = 30^2 - 10^2 = 900 - 100 = 800 cm^2


Hence, the surface area of the water in the bowl is

    {{{pi*r^2}}} = {{{3.14159265*800}}} = 2513.27412 cm^2,  or  2513.27  cm^2  (rounded).    <U>ANSWER</U>
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Solved.