Answer:
61.5°
Step-by-step explanation:
let's say the midle point as 0
mCOD = 180° - 140° = 40°
mEOF = mCOF - (mCOD + m DOE) = 180 - 40 - 83 = 57°
∆EFO is Isosceles Triangle with EO = FO then
mEFC = (180 - mEOF) : 2 = (180 - 57) : 2 = 61.5°
