KVPY2012MathematicsProperties of Triangles
In triangle ABC , let AD , BE and CF be the internal angle bisectors with D, E and F on the sides BC , CA and AB respectively. Suppose AD , BE and CF concur at I and B , D , I , F are concyclic, then IFD has measure -
Options
- A15^
- B30^
- C45^
- DAny value 90^
Correct answer
B. 30^
Step-by-step solution
array l AIC =180^ - ( A + C 2 ) =180^ - ( A + C 2 ) =90+ B 2 array Here :-90+ B 2 + B =180^ B =60^ This will be case of equilateral IFD =30^