- #1

- 1

- 0

x=e^tsint,

and y=e^tcost where (t) is greater than or equal to (0) and (t) is less

or equal to pi divided by (2).

when it is revolved about

a) the x-axis

b) the y-axis (approximation with calc. (how?))

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- Thread starter jrg_pz
- Start date

- #1

- 1

- 0

x=e^tsint,

and y=e^tcost where (t) is greater than or equal to (0) and (t) is less

or equal to pi divided by (2).

when it is revolved about

a) the x-axis

b) the y-axis (approximation with calc. (how?))

- #2

- 665

- 0

jrg_pz said:

x=e^tsint,

and y=e^tcost where (t) is greater than or equal to (0) and (t) is less

or equal to pi divided by (2).

when it is revolved about

a) the x-axis

b) the y-axis (approximation with calc. (how?))

Around the x-axis you have:

[tex]\text{SA}_x=2\pi\int_{a}^{b}f(x)\left(\sqrt{1+f'(x)^2}\right)dx[/tex]

...the y-axis you have:

[tex]\text{SA}_y=2\pi\int_{a}^{b}x\left(\sqrt{1+f'(x)^2}\right)dx[/tex]

And I assume you can figure out what f(x) and dx are in terms of your parametric equations...

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