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  1. AP Calculus
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Define 'cross-section' in the context of volumes.

A two-dimensional shape formed by slicing a three-dimensional solid.

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Define 'cross-section' in the context of volumes.

A two-dimensional shape formed by slicing a three-dimensional solid.

What is A(x)A(x)A(x) in the volume formula?

Area of the cross-section perpendicular to the x-axis at a given x.

Define the term 'solid of revolution'.

A 3D solid formed by rotating a 2D shape around an axis.

What does 'dxdxdx' represent in the volume integral?

Infinitesimally small thickness of the cross-section.

What is the significance of the interval [a,b][a, b][a,b]?

The limits of integration, defining the region's boundaries.

Define the term 'volume'.

The amount of three-dimensional space occupied by an object.

What is the formula for the area of a square?

Area of a square is s2s^2s2, where s is the side length.

What is the formula for the area of a rectangle?

Area of a rectangle is w∗hw*hw∗h, where w is the width and h is the height.

What is the meaning of 'perpendicular'?

Intersecting at or forming right angles (90 degrees).

Define 'definite integral'.

Integral evaluated between specific upper and lower limits, resulting in a numerical value.

Steps to find the volume of a solid with square cross-sections given two bounding curves.

  1. Find the intersection points of the curves (bounds). 2. Determine the side length s=f(x)−g(x)s = f(x) - g(x)s=f(x)−g(x). 3. Square the side length: A(x)=s2A(x) = s^2A(x)=s2. 4. Integrate: V=∫abA(x)dxV = \int_a^b A(x) dxV=∫ab​A(x)dx.

Steps to find the volume of a solid with rectangular cross-sections perpendicular to the y-axis.

  1. Express bounding curves as functions of y. 2. Find the intersection points (bounds). 3. Determine width and height as functions of y. 4. Find area: A(y)=w∗hA(y) = w*hA(y)=w∗h. 5. Integrate: V=∫cdA(y)dyV = \int_c^d A(y) dyV=∫cd​A(y)dy.

How to find the volume of a solid with square cross sections if given y=x2y = x^2y=x2 and y=4y = 4y=4?

  1. Find bounds: x=−2,2x = -2, 2x=−2,2. 2. s=4−x2s = 4-x^2s=4−x2. 3. A(x)=(4−x2)2A(x) = (4-x^2)^2A(x)=(4−x2)2. 4. V=∫−22(4−x2)2dxV = \int_{-2}^2 (4-x^2)^2 dxV=∫−22​(4−x2)2dx.

How to set up the integral for the volume of a solid with rectangular cross sections of height 3, perpendicular to the x-axis, bounded by y=xy = xy=x and y=x2y = x^2y=x2?

  1. Find bounds: x=0,1x = 0, 1x=0,1. 2. w=x−x2w = x - x^2w=x−x2. 3. h=3h = 3h=3. 4. V=∫013(x−x2)dxV = \int_0^1 3(x - x^2) dxV=∫01​3(x−x2)dx.

How to find the volume if the base is bounded by y=x3y=x^3y=x3, y=0y=0y=0, x=1x=1x=1 and the cross sections are squares perpendicular to the x-axis?

  1. Find bounds: x=0,1x = 0, 1x=0,1. 2. s=x3−0=x3s = x^3 - 0 = x^3s=x3−0=x3. 3. A(x)=(x3)2=x6A(x) = (x^3)^2 = x^6A(x)=(x3)2=x6. 4. V=∫01x6dxV = \int_0^1 x^6 dxV=∫01​x6dx.

How to find the volume if the base is bounded by x=y2x=y^2x=y2, x=4x=4x=4 and the cross sections are rectangles with height yyy perpendicular to the y-axis?

  1. Find bounds: y=−2,2y = -2, 2y=−2,2. 2. w=4−y2w = 4 - y^2w=4−y2. 3. h=yh = yh=y. 4. V=∫−22y(4−y2)dyV = \int_{-2}^2 y(4 - y^2) dyV=∫−22​y(4−y2)dy.

How do you determine the limits of integration when the region is bounded by y=x2y = x^2y=x2 and y=sqrtxy = sqrt{x}y=sqrtx?

Set x2=xx^2 = \sqrt{x}x2=x​ and solve for xxx to find the intersection points, which are the limits of integration.

What is the general strategy for solving volume problems with known cross-sections?

  1. Visualize the solid. 2. Determine the shape and area of the cross-section. 3. Find the limits of integration. 4. Set up and evaluate the integral.

If the cross-sections are perpendicular to the y-axis, how do you express the bounding curves?

Express the curves as functions of y, i.e., x=f(y)x = f(y)x=f(y) and x=g(y)x = g(y)x=g(y).

How do you handle a problem where the height of the rectangular cross-section is given as a function of x?

Include the height function in the area function A(x)=w(x)cdoth(x)A(x) = w(x) cdot h(x)A(x)=w(x)cdoth(x) and integrate with respect to x.

Volume of a solid with known cross-sections.

V=∫abA(x)dxV = \int_a^b A(x) dxV=∫ab​A(x)dx

Volume of a solid with square cross-sections.

V=∫abs2dxV = \int_a^b s^2 dxV=∫ab​s2dx

Volume of a solid with rectangular cross-sections.

V=∫abwcdothdxV = \int_a^b w cdot h dxV=∫ab​wcdothdx

Area of a square.

A=s2A = s^2A=s2

Area of a rectangle.

A=wcdothA = w cdot hA=wcdoth

How do you find the side length 's' of a square cross section when given two bounding curves f(x) and g(x), where f(x) is above g(x)?

s=f(x)−g(x)s = f(x) - g(x)s=f(x)−g(x)

How do you find the width 'w' of a rectangular cross section perpendicular to the y-axis when given two bounding curves f(y) and g(y), where f(y) is to the right of g(y)?

w=f(y)−g(y)w = f(y) - g(y)w=f(y)−g(y)

How to find the intersection points of two curves, f(x)f(x)f(x) and g(x)g(x)g(x)?

Set f(x)=g(x)f(x) = g(x)f(x)=g(x) and solve for xxx.

If integrating with respect to 'y', what does the volume formula become for general cross sections?

V=∫cdA(y)dyV = \int_c^d A(y) dyV=∫cd​A(y)dy

How do you express y=x3y = x^3y=x3 as a function of y?

x=y3x = \sqrt[3]{y}x=3y​