FD cut AB and AO at G and H ( see picture) Note that AD=AG=DG=6 OA= AG*2/√3 =12/√3 In triangle OHF , applying Pythagoras Theorem we get HF=3. √5 So x=HF-HD=3(√5-1) Peter Tran
Extend ED to cut AC at X and circle at Y EDXY ∥ AB So DE = 6 ; and XY = x (by symmetry) ED.DY = AD.DC x(6 + x) = 36 x²+ 6x = 36 (x + 3)² = 45 x = 3(√5 - 1)
http://img37.imageshack.us/img37/9728/problem700.png
ReplyDeleteFD cut AB and AO at G and H ( see picture)
Note that AD=AG=DG=6
OA= AG*2/√3 =12/√3
In triangle OHF , applying Pythagoras Theorem we get HF=3. √5
So x=HF-HD=3(√5-1)
Peter Tran
Extend ED to cut AC at X and circle at Y
ReplyDeleteEDXY ∥ AB
So DE = 6 ; and XY = x (by symmetry)
ED.DY = AD.DC
x(6 + x) = 36
x²+ 6x = 36
(x + 3)² = 45
x = 3(√5 - 1)