微积分AB:发现卷使用集成

Study concepts, example questions & explanations for Calculus AB

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Example Questions

Example Question #1 :Find Cross Sections: Squares & Rectangles

Find the volume of a pyramid whose base is a square with sides of lengthand whose height is.

Possible Answers:

Correct answer:

Explanation:

First, it is important to consider the shape of this solid. This solid is a pyramid, with one square face and four triangular faces. Through a relationship of similar triangles, we are able to relate the known information (a height ofand a base side length of) to our general variables for side lengthand height of the pyramid. We can think of this plotted on the coordinate plane, with the width of the pyramid solid being in thedirection.

Since the side lengthcan be squared to find a general formula for the area of the pyramid’s base, this can be applied to the volume using cross-sections formulaas the next step. Note that the equationsolved for above is in terms of. Our new volume function, therefore, is also in terms of

Because the pyramid reaches a maximum height of, and we assume the pyramid’s starting height is at, the appropriate bounds for the integral expression are:.

To wrap up this problem, combine the above information into one cohesive expression:

Example Question #2 :Find Cross Sections: Squares & Rectangles

Find the volume of the solid whose base is bounded byandand whose cross-sections are rectangles of heightand perpendicular to theaxis.

Possible Answers:

Correct answer:

Explanation:

The cross-sections are perpendicular to theaxis; therefore, the volume expression will be in terms of.

The area of a rectangle is. By applying this formula to our general volume formula, we get the following:.

Next, an expression formust be determined. The problem specifies the length (or height) of the rectangle cross-sections is. This just leaves the value of w to be found. The width of the rectangle will vary as the region creating the base of the solid varies. The region is defined by the area enclosed betweenand, therefore,.

Since the region is bounded byand, the base has the following domain:.

Putting this all together, we find the following:

Example Question #3 :Find Cross Sections: Squares & Rectangles

Identify the correct expression for the volume of a solid whose base is bounded by,andand whose cross-sections are squares perpendicular to theaxis.

Possible Answers:

Correct answer:

Explanation:

The cross-sections are perpendicular to theaxis; therefore, the volume expression will be in terms of.

The area of a square is, where s is the side length of the square. By applying this formula to our general volume formula, we get the following:.

Next, an expression for s2 must be determined. Because s should be the width of the solid’s base, the expression for that length can be used to solve for s2.

Since the region is bounded byand, the base has the following domain:.

Putting this all together, we find the following:

Example Question #4 :Find Cross Sections: Squares & Rectangles

Identify the correct expression for the volume of a solid whose base is bounded by a disk of radiusand whose cross-sections are squares parallel to theaxis.

Possible Answers:

Correct answer:

Explanation:

The cross-sections are parallel to theaxis; in other words, they are perpendicular to theaxis. This indicates that the expression should be in terms of.

Because the disk is of radius, the base is defined by the following formula:.

The area of a square is, with s being the side length. By applying this formula to our general volume formula, we get the following:.

The radiusdefines the bounds as being. Next,can be found by understanding thatdiffers as the width of the circle changes. The value ofis the distance from one side of the circle to the other at any given point along. The length of one side of the square, therefore, is.

Putting it all together, the following is obtained:

Example Question #5 :Find Cross Sections: Squares & Rectangles

Letbe the region bounded by,, and. Find the volume of the solid whose base is regionand whose cross-sections are squares perpendicular to theaxis.

Possible Answers:

Correct answer:

Explanation:

The cross-sections are perpendicular to theaxis; therefore, the volume expression will be in terms of.

The area of a square is, where s is the side length of the square. By applying this formula to our general volume formula, we get the following:.

Next, an expression formust be determined. Because s should be the width of the solid’s base, the expression for that length can be used to solve for.

Since the region is bounded byand, the base has the following domain:.

Putting this all together, we find the following:

Example Question #6 :Find Cross Sections: Squares & Rectangles

Letbe the region bounded byand. Find the volume of the solid whose base is regionand whose cross-sections are rectangles perpendicular to theaxis with height.

Possible Answers:

Correct answer:

Explanation:

The cross-sections are perpendicular to theaxis; therefore, the volume expression will be in terms of.

The area of a rectangle is. By applying this formula to our general volume formula, we get the following:.

Next, an expression formust be determined. The problem specifies the length (or height) of the rectangle cross-sections is. This just leaves the value ofto be found. The width of the rectangle will vary as the region creating the base of the solid varies. The region is defined by the area enclosed betweenand, therefore,.

Since the region is bounded byand, the base has the following domain:.

Putting this all together, we find the following:

Example Question #7 :Find Cross Sections: Squares & Rectangles

Letbe the region bounded by,and. Find the volume of the solid whose base is regionand whose cross-sections are rectangles perpendicular to theaxis with height.

Possible Answers:

Correct answer:

Explanation:

The cross-sections are perpendicular to theaxis; therefore, the volume expression will be in terms of.

The area of a rectangle is. By applying this formula to our general volume formula, we get the following:.

Next, an expression formust be determined. The problem specifies the length (or height) of the rectangle cross-sections is. This just leaves the value ofto be found. The width of the rectangle will vary as the region creating the base of the solid varies. The region is defined by the area enclosed between,and. The functionis rewritten in terms ofto become, because the final expression should reflect the fact that the cross sections should be written in terms of. Therefore,.

Since the region is bounded byand, the base has the following domain:.

Putting this all together, we find the following:

Example Question #8 :Find Cross Sections: Squares & Rectangles

Identify the correct expression for the volume of a solid whose base is bounded byand theaxis along, and whose cross-sections are rectangles perpendicular to theaxis with a height three times the width.

Possible Answers:

Correct answer:

Explanation:

The cross-sections are perpendicular to theaxis; therefore, the volume expression will be in terms of.

The area of a rectangle is. By applying this formula to our general volume formula, we get the following:.

Next, an expression formust be determined. The problem specifies the length (or height) of the rectangle cross-sections is three times the value of the width, or. The volume expression can now be modified:

This just leaves the value ofto be found. The width of the rectangle will vary as the region creating the base of the solid varies. The region is defined by the area enclosed betweenand, along. Therefore,.

Putting this all together, we find the following:

Example Question #9 :Find Cross Sections: Squares & Rectangles

Identify the correct expression for the volume of a solid whose base is bounded byandand whose cross-sections are squares perpendicular to theaxis.

Possible Answers:

Correct answer:

Explanation:

The cross-sections are perpendicular to theaxis; therefore, the volume expression will be in terms of.

The area of a square is, whereis the side length of the square. By applying this formula to our general volume formula, we get the following:.

Next, an expression formust be determined. Because s should be the width of the solid’s base, the expression for that length can be used to solve for.

Since the region is bounded byand, the base has the following domain:.

Putting this all together, we find the following:

Example Question #10 :Find Cross Sections: Squares & Rectangles

Identify the correct expression for the volume of a solid whose base is bounded byandalongand whose cross-sections are squares perpendicular to theaxis.

Possible Answers:

Correct answer:

Explanation:

The cross-sections are perpendicular to theaxis; therefore, the volume expression will be in terms of.

The area of a square is, whereis the side length of the square. By applying this formula to our general volume formula, we get the following:.

Next, an expression formust be determined. Becauseshould be the width of the solid’s base, the expression for that length can be used to solve for.

Putting this all together, we find the following:

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