As shown in the figure, it is proved that the triangle AFC∽AFG

∵ are two congruent isosceles right triangles.

∴∠C=∠FAG

There is also a male role ∠AFC.

Two angles of two triangles are equal, and the third angle must be equal.

∴∠FAC=∠FGA

That is, the triangles are equal,

∴△AFG∽△AFC