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Which shape could not be the intersection of a cone and a plane?

Question 1 options
rectangle
ellipse
circle
parabola

questions 2 and 3 (has a picture)

Which three-dimensional figure could have a rectangular cross-section?

Question 4 options:
pentagonal pyramid
cylinder
cone
tetrahedron

Claude has a piece of cheese in the shape of a cone. He uses a straight cut to slice off a smaller piece. Which shape could be one of the faces of Claude’s smaller piece of cheese?
Question 5 options:
ellipse
square
pentagon
parallelogram

Which shape could not be the intersection of a cone and a plane? Question 1 options-example-1
Which shape could not be the intersection of a cone and a plane? Question 1 options-example-1
Which shape could not be the intersection of a cone and a plane? Question 1 options-example-2
User Noctiluque
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7.6k points

1 Answer

2 votes
Question 1

An ellipse, circle and parabola are all possible figures we can make if we intersect a plane and a cone. These are called conic sections.

A rectangle is NOT a conic section and not possible to form it with an intersection of a cone and a plane.

Answer: Choice A) rectangle

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Question 2

The shaded cross section is a parabola. It stretches onward forever as you move down the bottom cone. This plane won't intersect the top cone at all.

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Question 3

Spinning the rectangle around that line will create a flattened cylinder, which is what choice A is showing. Think of a fan blade spinning really fast, or a revolving door.

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Question 4

A pentagonal pyramid has a pentagonal cross section. So that rules out choice A.

A cylinder could have a rectangular cross section if the plane is perpendicular to the base.

Choice C is eliminated since we can only form triangles or circles as cross sections here.

A tetrahedron could have a square cross section, which is a special case of a rectangle, making choice D a possibility as well.

So the answer is either choice B or choice D. If your teacher is excluding squares, then we can eliminate choice D making B as the only answer. Though I'm not 100% sure on this one.

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Question 5

Claude is forming a conic section so he could form an ellipse. The other choices (square, pentagon, parallelogram) are not possible cross sections of a cone.

User Darran
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8.0k points

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