In a triangle ABC, points M and N are on sides AB and AC, respectively,
such that MB = BC = CN. Let R and r denote the circumradius and the inradius of the
triangle ABC, respectively. Express the ratio MN/BC in terms of R and r.
In a triangle ABC, points M and N are on sides AB and AC, respectively,
such that MB = BC = CN. Let R and r denote the circumradius and the inradius of the
triangle ABC, respectively. Express the ratio MN/BC in terms of R and r.