Answer:
O is the center of the circle with radius IE(=ID=EF)
Step-by-step explanation:
Join all 3 points D, E, F, forming the triangle DEF.
Let the midpoint of EF be M and the midpoint of ED be N. (first picture)
Join point I to E, D and F.
Since IN is both an altitude and median to triangle EID, then triangle EID is an isosceles triangle, and IE=ID
similarly, we see that IE=IF.
conclusion: IE=ID=EF.
Answer:
-3.33333333333
Step-by-step explanation:
