How to find the surface area of a polyhedron - Math

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Question

Find the surface area of the following half-cylinder.

Half_cylinder

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Answer

The formula for the surface area of a half-cylinder must include one-half of the surface area of a cylinder, which would be:

We also need to add the area of the new rectangular face that is created by cutting the cylinder in half. The area of this rectangle would be:

where the length of the rectangle is the same as the height of the half-cylinder, and the width of the rectangle is the same as the diameter of the base of the half-cylinder. So we can rewrite the area of the rectangle as:

Now we can combine the two area formulas to find the total surface area of the half-cylinder:

where is the radius of the base and is the length of the height, and is the diameter of the base.

Plugging in our values, we get:

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