Question Number 145174 by mathdanisur last updated on 02/Jul/21
Answered by mr W last updated on 02/Jul/21
Commented by mr W last updated on 02/Jul/21
$${OD}={OB} \\ $$$${CD}={CB} \\ $$$$\Rightarrow\angle{OCD}=\angle{OCB}=\mathrm{45}° \\ $$$$\angle{CFB}=\angle{FED}=\angle{FBD}=\mathrm{45}°=\angle{OCB} \\ $$$$\Rightarrow{EF}//{OC} \\ $$
Commented by mr W last updated on 02/Jul/21
$${E}\:{mustn}'{t}\:{be}\:{midpoint}\:{of}\:{AD}. \\ $$
Commented by mathdanisur last updated on 02/Jul/21
$${a}\:{lot}\:{cool}\:{Ser},\:{thankyou}.. \\ $$