Answer:
∠ DFG = 48°
Explanation:
the central angle is equal to the measure of the arc that subtends it.
since EOG is the diameter of the circle with central angle of 180° , then
arc EG = 180°
the inscribed angle EGD is half the measure of the arc ED that subtends it, so
arc ED = 2 × ∠ EGD = 2 × 42° = 84° , then
ED + DG = EG , that is
84° + DG = 180° ( subtract 84° from both sides )
DG = 96°
Then
∠ DFG =
× EG =
× 96° = 48°