Given:
The measure of ∠EGF is 51°
We need to determine the measure of ∠EHF
Measure of ∠EHF:
By inscribed angle theorem, we know that, "if two inscribed angles of a circle intercept the same arc then the angles are congruent".
Applying the theorem, we have that the two inscribed angles of a circle intercepting the same arc are ∠G and ∠H
Then, the two angles are congruent.
Thus, we have;
∠G ≅ ∠H
Therefore, the measure of ∠G = ∠H = 51°
Hence, the measure of ∠EHF = 51°