Calculus Volume 2 · free preview

Arc Length of a Curve and Surface Area

Arc length integrates the infinitesimal hypotenuse of curve pieces into a total length formula, and rotating a curve about an axis sweeps a surface whose area integrates circumferential bands.

1. The arc length formula

The arc length formula

2. Symmetry and special cases

Symmetry and special cases

3. Surface area of revolution

Surface area of revolution

4. Work and the physical template

Work and the physical template

5. Arc length integrand

For a curve y = f(x) on [a, b], which integrand gives the arc length?

6. Line segment check

The arc length formula applied to the line y = mx on [0, a] gives what length?

7. Surface area band

A piece of curve of length ds at distance r from the axis of rotation sweeps what band area?

8. Sphere surface area

Rotating the semicircle y = sqrt(r^2 - x^2) about the x axis, what surface area integral gives the sphere?

9. Gabriel's horn paradox

Rotating y = 1/x on [1, infinity) about the x axis gives a surface with infinite area but finite volume. What does this demonstrate?

10. Which curves have closed-form lengths

For which curve does the arc length integral on a finite interval evaluate in elementary closed form?

11. Arc length of a simple curve

For y = x on [0, 1], the arc length integral is the integral of sqrt(2) dx. What length results? Answer like sqrt(2).

12. Slant height formula

The cone's surface area from rotation is pi r times the slant height, a single letter usually used for it. What letter? Answer with one lowercase letter.

13. Sphere from rotation

The sphere's surface area integral 2 pi integral of r dx from -r to r evaluates to what multiple of pi r^2? Answer with a number.

14. ds expression

The arc length element ds equals sqrt of 1 plus a squared derivative. As two letters followed by prime notation, what is that derivative? Answer like f'.

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