Finding radius of circle inscribed in a triangle

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SUMMARY

The discussion centers on calculating the radius of the inscribed circle (inradius) of a triangle given its side lengths. The problem is solvable using basic algebra and geometry, particularly through the application of circle theorems and trigonometry. The participant noted that the relationship between tangents and the radius is crucial, specifically that the angle formed by a tangent and the radius at the point of contact is 90 degrees. Additionally, the equality of tangents from a point outside the circle is relevant to the solution.

PREREQUISITES
  • Understanding of triangle properties and the concept of inradius
  • Familiarity with circle theorems, particularly tangent properties
  • Basic knowledge of trigonometry
  • Ability to manipulate algebraic expressions
NEXT STEPS
  • Study the formula for the inradius of a triangle: r = A/s, where A is the area and s is the semi-perimeter
  • Learn about the properties of tangents to circles and their relationship with radii
  • Explore the application of Heron's formula for calculating the area of a triangle
  • Investigate the implications of triangle types (e.g., right triangle) on inscribed circles
USEFUL FOR

Students studying geometry, educators teaching triangle properties, and anyone interested in solving problems related to inscribed circles in triangles.

Bohrok
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Homework Statement



Someone gave me this problem: finding the radius of the circle inscribed in the triangle with the given lengths.

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The Attempt at a Solution



The person asking about this problem said it was taken from a beginning algebra textbook. I tried figuring it out using just basic algebra, but I couldn't make any progress. Is this problem solvable with basic algebra/geometry? Would it be any easier if it were a right triangle?
 
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What I can deduce that you must use are some of the circle theorems, such as the angle made by a tangent and radius at the point of contact is 90°, as well as possibly some trigonometry.

I believe that the two tangents that meet (made by the 4 unit and 3 unit line) are both equal by one of the circle theorems.
 

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