question_answer

Internal bisector of ZA of triangle ABC meets side BC at D. A line drawn through D perpendicular to AD intersects the side AC at E and the side AB at F. If a, b, c represent sides of A ABC then

A)  AE is HM of b and c

B)  \[AD=\frac{2\,\,bc}{b+c}\,\,\cos \,\,\frac{A}{2}\]           

C)  \[EF=\frac{4\,\,bc}{b+c}\,\,\sin \,\,\frac{A}{2}\]

D)  The triangle AEF is isosceles

E)  All of these