The base of a solid is the region enclosed by the graphs of y=sin(x) and y=4−x, between x=2 and x=7.Cross sections of the solid perpendicular to the x-axis are rectangles whose height is 2x.Which one of the definite integrals gives the volume of the solid?Choose 1 answer:(A) ∫27[(4−x)2−sin2(x)]dx(B) ∫27[sin(x)+x−4]⋅2xdx(C) ∫27[sin2(x)−(4−x)2]dx(D) ∫27[4−x−sin(x)]⋅2xdx
Q. The base of a solid is the region enclosed by the graphs of y=sin(x) and y=4−x, between x=2 and x=7.Cross sections of the solid perpendicular to the x-axis are rectangles whose height is 2x.Which one of the definite integrals gives the volume of the solid?Choose 1 answer:(A) ∫27[(4−x)2−sin2(x)]dx(B) ∫27[sin(x)+x−4]⋅2xdx(C) ∫27[sin2(x)−(4−x)2]dx(D) ∫27[4−x−sin(x)]⋅2xdx
Integrate Area of Cross Sections: To find the volume of the solid, we need to integrate the area of the cross sections along the x-axis from x=2 to x=7. The area of each rectangular cross section is given by the difference in the y-values of the two functions (the height of the rectangle) times the given height of the rectangle (2x). The correct integral will have the form ∫[f(x)−g(x)]⋅h(x)dx, where f(x) and g(x) are the y-values of the top and bottom functions, respectively, and h(x) is the height of the rectangle.
Determine Top Function: First, we need to determine which function is on top (has a larger y-value) between x=2 and x=7. Since y=4−x is a decreasing function and y=sin(x) oscillates between −1 and 1, y=4−x will be on top for the entire interval from x=2 to x=7.
Calculate Cross Section Area: The area of each cross section is therefore (4−x−sin(x)) times the height of the rectangle, which is 2x. This gives us the integrand (4−x−sin(x))×2x.
Find Correct Integral: The correct integral for the volume of the solid is therefore ∫x=2x=7(4−x−sin(x))⋅2xdx. This matches option (D).
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