In an acute-angled triangle ABC the angle at B is greater than 45∘. Points D,E,F are the feet of the altitudes from A,B,C respectively, and K is the point on segment AF such that ∠DKF=∠KEF.
(a) Show that such a point K always exists.
(b) Prove that KD2=FD2+AF⋅BF. geometrygeometric transformationreflectiongeometry unsolved