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[sin(x)+x−4]⋅2xdx(B) ∫27[sin2(x)−(4−x)2]dx(C) ∫27[4−x−sin(x)]⋅2xdx(D) ∫27[(4−x)2−sin2(x)]dx
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[sin(x)+x−4]⋅2xdx(B) ∫27[sin2(x)−(4−x)2]dx(C) ∫27[4−x−sin(x)]⋅2xdx(D) ∫27[(4−x)2−sin2(x)]dx
Cross-Sectional Area Calculation: The volume of a solid with known cross-sectional area perpendicular to the x-axis can be found by integrating the area of the cross-sections along the x-axis. 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 in this case). Therefore, the area A(x) of a cross-section at a point x is A(x)=(upper function−lower function)×height. The upper function is y=4−x, and the lower function is y=sin(x). So, A(x)=(4−x−sin(x))×2x.
Setting up the Integral: We need to set up the integral of A(x) from x=2 to x=7 to find the volume. The integral that represents the volume V is V=∫27A(x)dx=∫27(4−x−sin(x))⋅2xdx.
Comparison with Options: Comparing the integral we found with the options given, we see that option (C) matches our integral: (C)∫27[4−x−sin(x)]⋅2xdx.
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