According to the given information we can prove that those angles are congruent using the following statements and reasons.
S1-KG is the perpendicular bisector of FH
R1-Given
S2-FG ≅ GH
R2-Definition of bisector
S3-KG ≅ KG
R3-Reflexive property
S4-Angle KGF ≅ Angle KGH
R4-All perpendicular angles are congruent
S5-Triangle KGH ≅ Triangle KGF
R5-Side Angle Side Theorem of Congruence