CTK Exchange
Front Page
Movie shortcuts
Personal info
Awards
Reciprocal links
Terms of use
Privacy Policy

Interactive Activities

Cut The Knot!
MSET99 Talk
Games & Puzzles
Arithmetic/Algebra
Geometry
Probability
Eye Opener
Analog Gadgets
Inventor's Paradox
Did you know?...
Proofs
Math as Language
Things Impossible
My Logo
Math Poll
Other Math sit's
Guest book
News sit's

Recommend this site

Manifesto: what CTK is about Search CTK Buying a book is a commitment to learning Table of content Things you can find on CTK Chronology of updates Email to Cut The Knot Recommend this page

CTK Exchange

Subject: "Geometry - Draw the third circle such that..."     Previous Topic | Next Topic
Printer-friendly copy     Email this topic to a friend    
Conferences The CTK Exchange This and that Topic #723
Reading Topic #723
Deep G
Member since Nov-6-05
Jul-10-06, 03:39 PM (EST)
Click to EMail Deep%20G Click to send private message to Deep%20G Click to view user profileClick to add this user to your buddy list  
"Geometry - Draw the third circle such that..."
 
   Hi,

I love to sometimes think of how I could construct simple Geometrical figures (a circle in the following case) under different 'circumstances' (or should i say constraints listed in a problem). The following two problems occured to me last night out of sheer thought.
Intuition (with a little imagination) tells me that the following two constructions are definitely possible (i.e. the give information is not insufficient AND there EXISTS a third circle as a solution to the two problems.)

I have two coplanar circles C1 and C2 having radii r1 and r2 with r2>r1 and distance between the two centres exceeding the sum of r1 and r2. I also have a point P in the same plane as that of C1 and C2 such that it lies in the exterior of both C1 and C2.
Draw a circle C3 that is tangential to C1 and C2 and passing through P.

The solution to the above problem might also extend to this problem:
I have two coplanar circles C1 and C2 having radii r1 and r2 with r2>r1 and C1 lying entirely inside C2 (thus they do not intersect at all). I have a point P that lies in the exterior of C1 but in the interior of C2.
Draw a circle C3 that is tangential to C1 and C2 and passing through P.

PS: I hope to have provided unambiguous and complete information in the above problems. :-) . Please post your reply to get clarified over any issues you might have.

Thanks,

Deep G.
d:-)


  Alert | IP Printer-friendly page | Reply | Reply With Quote | Top
alexbadmin
Charter Member
1859 posts
Jul-10-06, 04:12 PM (EST)
Click to EMail alexb Click to send private message to alexb Click to view user profileClick to add this user to your buddy list  
1. "RE: Geometry - Draw the third circle such that..."
In response to message #0
 
   I believe you dreamed up specific cases of the Apollonius problem:

https://www.cut-the-knot.org/Curriculum/Geometry/Apollonius.shtml


  Alert | IP Printer-friendly page | Reply | Reply With Quote | Top

Conferences | Forums | Topics | Previous Topic | Next Topic

You may be curious to have a look at the old CTK Exchange archive.
Please do not post there.

Copyright © 1996-2018 Alexander Bogomolny

Search:
Keywords:

Google
Web CTK