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**ShivamS****Member**- Registered: 2011-02-07
- Posts: 3,629

Please check the following.

Vector r = (e^3t, sin(2t), t^2)

What is vector r(t) prime? I am getting (3e^3t, 2cos(2t), 2t)

Compute the unit tangent vector T(t) and do not simplify the answer. I get vector T(t) = (3e^3t, 2cos(2t), 2t) divided by square root of (9e^6t + 4cos^2(2t) +4t^2)

Thanks in advance.

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**anonimnystefy****Real Member**- From: The Foundation
- Registered: 2011-05-23
- Posts: 15,657

That look correct!

Here lies the reader who will never open this book. He is forever dead.

Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment

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**ShivamS****Member**- Registered: 2011-02-07
- Posts: 3,629

Thanks a lot.

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**anonimnystefy****Real Member**- From: The Foundation
- Registered: 2011-05-23
- Posts: 15,657

You're welcome.

Here lies the reader who will never open this book. He is forever dead.

Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment

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**ShivamS****Member**- Registered: 2011-02-07
- Posts: 3,629

More stuff: g(t) = 4t+1 what is d/dt r(g9t))

I get 4{3e^3(4t+1), 2cos[2(4t+1)], 2(4t+1)}

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,532

hi

r(g9t)) I take it that's r(g(t)) so chain rule

dr/dt = dr/dg x dg/dt

Take the first component. I'm thinking that is

Or am, I mixing up here?

so

diff gives

Bob

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

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**ShivamS****Member**- Registered: 2011-02-07
- Posts: 3,629

d/dt r(g(t)) = g'(t)r'(g(t)) = d/dt(4t+1)r'(4t+1)

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**anonimnystefy****Real Member**- From: The Foundation
- Registered: 2011-05-23
- Posts: 15,657

Hi Shivamcoder3013

I would say that is correct as well.

Here lies the reader who will never open this book. He is forever dead.

Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,532

Sorry I put an edit in above.

Please look.

Back later

Bob

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

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**ShivamS****Member**- Registered: 2011-02-07
- Posts: 3,629

Thanks.

*Last edited by Shivamcoder3013 (2013-06-24 04:28:56)*

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,532

hi Shivamcoder3013

Your notation is confusing me. I'd do this like this:

Bob

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

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**ShivamS****Member**- Registered: 2011-02-07
- Posts: 3,629

That is not different from my answer.

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,532

hi Shivamcoder3013

Oh, that's a big relief for me. Somehow, I missed that. Sorry I've dragged this thread out longer than was necessary

Bob.

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**ShivamS****Member**- Registered: 2011-02-07
- Posts: 3,629

No problem. Thanks both of you.

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