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Arc Length and Surface Area of y equals ln of x squared minus one from x equals two to x equals eight

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Consider the arc on the curve y=ln(x21)y=\ln(x^2-1) from x=2x=2 to x=8x=8. Compute the following: (a) Find the arc length. (b) Find the surface area when the arc is rotated about the x-axis. (c) Find the surface area when the arc is rotated about the y-axis.

This problem involves finding both the arc length and the surface area of a curve when rotated about different axes. These types of problems are fundamental in calculus, particularly in understanding how to compute lengths and areas of curves that cannot be easily simplified into basic geometric shapes. When calculating arc length, we rely on integrating the square root of 1 plus the square of the derivative of the function. This requires understanding how derivatives act on a function and the geometric interpretation of these operations.

For surface area calculations, the problem asks for two scenarios: rotating about the x-axis and the y-axis. Each scenario involves setting up and solving definite integrals based on the original function's relation to the chosen axis of rotation. Rotating a curve around the x-axis typically involves using the formula for surface area: integration of 2 pi times the function times the arc length differential. Meanwhile, rotating around the y-axis requires adjusting the formula to accommodate the change of rotation direction, often incorporating an integral with respect to y. Mastering these calculations equips students with a deeper understanding of the symmetry and geometry inherent in calculus problems involving curves.

Posted by grwgreg 5 days ago

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