# Circles Connected with a Triangle

1) If $r$ denotes in-radius, then

2) Circum radius $R$ is given by

3) If ${r_1},{r_2},{r_3}$ denotes $e -$radii, then

4) ${r_1} + {r_2} + {r_3} - r = 4R$

5) In an equilateral triangle $r:R:{r_1} = 1:2:3$