+0  
 
0
101
1
avatar+208 

In the diagram, four circles of radius 1 with centres \(P, Q, R,\) and \(S \) are tangent to one another and to the sides of \(\triangle ABC \), as shown.

The radius of the circle with center \(R\) is decreased so that

the circle with center \(R\) remains tangent to \(BC\),

the circle with center \(R\) remains tangent to the other three circles, and

the circle with center \(P\) becomes tangent to the other three circles.


The radii and tangencies of the other three circles stay the same. This changes the size and shape of \(\triangle ABC\).  \(r\) is the new radius of the circle with center \(R\)\(r\) is of the form \(\frac{a+\sqrt{b}}{c}\). Find \(a+b+c\).

 Jun 6, 2021
 #1
avatar
0

r = (2 + sqrt(3))/4, so a + b + c = 2 + 3 + 4 = 9.

 Jun 6, 2021

37 Online Users

avatar