You can use the fact that along with the surface area of hemisphere, you need to add the surface area of the circle that's on the top of each hemisphere.(hemisphere means half of sphere)
The surface area of each half of the styrofoam ball is [tex]3\pi r^2 \: \rm unit^2[/tex]
What is the surface area of a hemisphere?
Surface area of sphere = [tex]4 \pi r^2[/tex] sq. units where r is radius of sphere.
Since hemisphere is half of the sphere, thus,
Surface area of hemisphere = [tex]2\pi r^2[/tex] sq. units.
Using the above formula along with the area of circle to find the needed surface area
Since the foam ball is not hollow, if we slice it in half, each of the half piece is having surface = outer half sphere's surface + that circle which is formed due to slicing the ball
Thus, surface area of each half of the Styrofoam ball is calculated as
Surface area = Surface area of hemisphere + area of circle
Let the ball had radius r, then we have the needed surface area as:
[tex]S = 2\pi r^2 + \pi r^2 = 3\pi r^2 \: \rm unit^2[/tex]
S is surface area of each half of the styrofoam ball.
Learn more about surface area of a hemisphere here:
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