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Please help with 9-12

Please help with 9-12-example-1
User Rexy Hoang
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1 Answer

1 vote

Answer:

9. Cylinder

10. 14 in

11. 20π in³

12. circle, ellipse, rectangle, truncated ellipse

Explanation:

You want the solid obtained by revolving a rectangle around one edge, the perimeter of the rectangle, the volume of the solid, and the names of at least 2 cross sections of the solid.

9. Solid of revolution

Every point on the outside edge of the solid will be 2 inches from the center axis. That is, the cross section perpendicular to the axis of revolution will be a circle. The solid is a cylinder.

10. Perimeter

The perimeter of a rectangle is given by the formula ...

P = 2(L +W)

P = 2(2 in + 5 in) = 2(7 in) = 14 in

The perimeter is 14 inches.

11. Volume

The radius of the cylinder is 2 inches, and its height is 5 inches. The volume is given by ...

V = πr²h

V = π(2 in)²(5 in) = 20π in³

The volume is 20π cubic inches, about 62.8 cubic inches.

12. Cross sections

The four attachments show possible cross sections of the cylinder. They include a circle, ellipse, rectangle, and truncated ellipse. The truncated ellipse may be cut off on one or both ends.

Please help with 9-12-example-1
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Please help with 9-12-example-4
User Christopher Milne
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