Precalculus Help: Find the Equation of a Circle Tangent to a Line

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Discussion Overview

The discussion revolves around finding the equation of a circle that is tangent to a specified line at a given point, with the center of the circle constrained to lie on another line. Participants explore methods to determine the center point and radius of the circle, as well as seek additional resources for precalculus study.

Discussion Character

  • Homework-related
  • Mathematical reasoning

Main Points Raised

  • Jennifer presents the problem of finding the equation of a circle tangent to the line 2x-y+1=0 at the point (2, 5), with the center on the line x+y=9.
  • One participant suggests writing an equation for a line orthogonal to the tangent line that passes through (2, 5) to find the center of the circle.
  • This participant also proposes calculating the radius as the distance between the center and the point of tangency.
  • Another participant expresses uncertainty about their approach, indicating a lack of confidence in their mathematical abilities.
  • A separate post diverges from the main problem, asking for additional tools or resources to aid in precalculus studies.

Areas of Agreement / Disagreement

There is no consensus on the method to solve the problem, as participants offer different approaches and express uncertainty about their suggestions. The discussion remains unresolved regarding the correct steps to find the equation of the circle.

Contextual Notes

Participants have not fully explored the implications of the orthogonal line or the distance calculation, leaving some assumptions unaddressed. The discussion also includes a shift in focus to general precalculus resources, which may not directly relate to the original problem.

JeNNeHJo
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I was wondering if anyone could help me with this problem

A circle is tanget to line 2x-y+1=0, at point (2, 5), and the center point is on line, x+y=9. Determine the equation (in general form) of the circle.

Normally I can do this sort of problem but I am having a hard time with this one. I don't know how to determine the center point or radius...frustrating..


Thanks, Jennifer
 
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JeNNeHJo said:
I was wondering if anyone could help me with this problem

A circle is tanget to line 2x-y+1=0, at point (2, 5), and the center point is on line, x+y=9. Determine the equation (in general form) of the circle.

Normally I can do this sort of problem but I am having a hard time with this one. I don't know how to determine the center point or radius...frustrating..


Thanks, Jennifer
This might be wrong because I'm basically an idiot, but here's what I'd do,…

Write an equation for a line that is orthogonal to 2x-y+1=0 and also passes through point (2,5).

Then solve for where that line and x+y=9 cross. That point must be the center of the circle.

The radius of the circle is the distance between those two points and the rest is history, … Er,.. I mean, mathematics.

I think that'll do it, but I'm sure some real mathematicians will come along and correct me if I'm wrong. :wink:
 
NeutronStar said:
This might be wrong because I'm basically an idiot, but here's what I'd do,…

Write an equation for a line that is orthogonal to 2x-y+1=0 and also passes through point (2,5).

Then solve for where that line and x+y=9 cross. That point must be the center of the circle.

The radius of the circle is the distance between those two points and the rest is history, … Er,.. I mean, mathematics.

I think that'll do it, but I'm sure some real mathematicians will come along and correct me if I'm wrong. :wink:

That's what I would've done.
 
hello,

i just starting taking classes for pre-cal... haven't taken classes in yrs... besides the calculator and the textbook - what else can i buy to help me with this class? any tools?? (besides a tutor)

Thanks in advance!

A
 

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