Temistocle Birsan, Bounds for elements of a triangle expressed by R, r, and s,
Forum Geometricorum, 15 (2015) 99--103.

Abstract. Assume that a triangle is defined by the triple (R,r,s) fulfilling Euler's and Blundon's inequalities (R - the circumradius, r - the inradius, s - the semiperimeter). We find some bounds for the trigonometric functions of the angles and for the sides of the triangle expressed by R and r.

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