external section formula

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kh ibrahim
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Joined: Mon May 09, 2016 11:18 am

external section formula

Unread post by kh ibrahim » Fri Oct 07, 2016 2:37 am

I'm facing trouble in the external section formula in vectors.here it is
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external section formula.I don't know which is correct.need the solution
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kh ibrahim
Posts: 17
Joined: Mon May 09, 2016 11:18 am

Re: external section formula

Unread post by kh ibrahim » Fri Oct 07, 2016 2:40 am

the second part of that external section formula.
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external section formula.the second part is here.picture
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kh ibrahim
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Re: external section formula

Unread post by kh ibrahim » Fri Oct 07, 2016 2:41 am

I don't know which is correct or why that would be correct.

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Phlembac Adib Hasan
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Re: external section formula

Unread post by Phlembac Adib Hasan » Fri Oct 07, 2016 8:51 am

Both of the formulae are correct. $C$ is not on the same end of $\vec{AB}$ in both proofs. That's why the formula changes.

Actually, there is no special formula called external section formula. It's just the internal section formula with one of the ratios being negative.
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kh ibrahim
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Joined: Mon May 09, 2016 11:18 am

Re: external section formula

Unread post by kh ibrahim » Fri Oct 07, 2016 1:12 pm

How can a ratio be negative?Is it because of different direction?

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Phlembac Adib Hasan
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Re: external section formula

Unread post by Phlembac Adib Hasan » Sun Oct 09, 2016 10:02 am

Yeah. Vector lengths are direction sensitive.
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kh ibrahim
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Joined: Mon May 09, 2016 11:18 am

Re: external section formula

Unread post by kh ibrahim » Sun Oct 09, 2016 2:17 pm

Lets talk out of vectors.Supposing if a point C divides a line segment AB externally what would it mean?Will it mean C is closer to A or B?Why would it mean so?

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