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In this video, let's discuss the external angle dissector theorem.

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All right, so over here we have a triangle and side beauty is extended to T. Right now.

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We know that this angle over here, that's angle t v Q is an external angle.

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All right, now let's construct the efforts that this angle over here is equal to this angle or here

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that is D.F. is the angle by sector of angle dequeue.

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All right.

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So these two angles are equal.

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Now, it's easier to write the ratio as per the external angle bisecting theorem if you imagine the

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external angle by sector to be an internal angle by dissector.

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So that's a trick to write the ratio correctly.

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So let's quickly imagine that D.F. was the internal angle by sector over here.

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Now we know how to write the ratio in this case.

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Right.

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The ratio would be pretty by dequeue is equal to PEF by RFQ.

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So let me write that over here.

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We have already seen that right now over here, having got the ratio, we just need to remove this part

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and keep the angle by sector as the external angle by sector.

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And this ratio is the correct ratio over here as well that is very divided by dequeue will be equal

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to P F, divided by F Q and that is the external angle by sector here.