MathDB
FN is tangent to the circle through B, I,C, incenter and circumcircle related

Source: Dutch IMO TST3 2018 p4

August 5, 2019
circumcircletangentgeometryincenterarc midpoint

Problem Statement

In a non-isosceles triangle ABCABC the centre of the incircle is denoted by II. The other intersection point of the angle bisector of BAC\angle BAC and the circumcircle of ABC\vartriangle ABC is DD. The line through II perpendicular to ADAD intersects BCBC in FF. The midpoint of the circle arc BCBC on which AA lies, is denoted by MM. The other intersection point of the line MIMI and the circle through B,IB, I and CC, is denoted by NN. Prove that FNFN is tangent to the circle through B,IB, I and CC.