Find Type of Triangle Given r1-r2-r3

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Homework Help Overview

The discussion revolves around identifying the type of triangle based on the relationship involving the ex-radii (r1, r2, r3) and the circumradius (R). The original poster presents a mathematical expression relating these elements but is uncertain about the next steps in their reasoning.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants explore the definitions of ex-radii and their relationships to the circumradius. There are attempts to manipulate the given equation, and questions arise about the meanings of the variables involved.

Discussion Status

Some participants have provided clarifications regarding the terms used in the problem, and one participant suggests expressing certain variables in terms of the circumradius and trigonometric functions. The discussion appears to be progressing with helpful guidance being offered.

Contextual Notes

There is a noted lack of familiarity with the concept of ex-radii among some participants, which may affect their understanding of the problem. The original poster's expressions involve specific relationships that may require further exploration or clarification.

utkarshakash
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Homework Statement


If in any triangle r=r1-r2-r3, then which type of triangle is it?
r1,r2,r3 denotes ex-radii.

The Attempt at a Solution



4R = r1+r2+r3-r

r2+r3 = 2R

I can't figure out what to do next.
 
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What are ex-radii? I've never heard that term before. Also, what are ##r## and ##R## supposed to denote?
 
vela said:
What are ex-radii? I've never heard that term before. Also, what are ##r## and ##R## supposed to denote?

Less encountered in geometry problems but they do exist. :)

http://en.wikipedia.org/wiki/Incircle_and_excircles_of_a_triangle

utkarshakash said:

Homework Statement


If in any triangle r=r1-r2-r3, then which type of triangle is it?
r1,r2,r3 denotes ex-radii.

The Attempt at a Solution



4R = r1+r2+r3-r

r2+r3 = 2R

I can't figure out what to do next.

Hi utkarshakash! :)

You are almost there. Can you express ##r_2## and ##r_3## in terms of R, the sines and cosines of three angles of the triangle?
 

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