# PSAT 1.8 Math Narrative Walkthrough

PSAT 1.8 Math Narrative Walkthrough. Which description of a circle corresponds to the equation?

 Math Additional Topics in Math PSAT PSAT MathPSAT Math Diagnostic PSAT Math Math Diagnostic

### Transcript

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answers Okay so we're looking for the description of a

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circle This is important stuff Because of a circle ever

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hijacks your car you'll want to be able to give

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a clear description Otherwise he might just roll free Were

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given an equation X plus two squared Plus why Plus

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three great design Yeah Kind of like that princes and

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that circle But we don't see anything about hair eye

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color here so probably need you bit of math Unfortunately

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not too much though because if we know the standard

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equation of a circle and hopefully we dio then this

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problem is a snap Here it is X minus h

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squared plus y minus k squared equals r square Well

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gee golly will occurs That looks an awful lot like

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our equation already So we really don't have to do

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Too much with it Since the center of a circle

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is represented by the point h k in the standard

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equation we just have to look at the numbers in

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our equation and see how they line up while the

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two here is our age And the three here is

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rk But notice that there are a couple minus signs

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in the standard equation meaning we'll have to change the

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signs on our numbers to making the center of the

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circle negative too negative Three now for the radius which

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is the number on the other side of the equal

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sign But the radius isn't r squared it just plain

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old are so we'll need to reverse the operation here

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Taking the square root of nine You get three just

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to make sure we can plug everything back into the

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standard equation and yep checks out there we go there

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to describe this circle We'd say it has a center

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located at point Negative Too Negative three with a radius

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