Mathematics

These two triangles have all three pairs of corresponding sides equal, which means they're congruent—they're the same triangle, just possibly rotated or reflected. The key insight is that congruent triangles have equal corresponding angles. Since the sides match up in a specific order ($AB = DE$, $BC = EF$, $CA = FD$), you can identify which angles correspond to each other and use that correspondence to find $\angle B$ from the given information about $\angle E$.

These two triangles have all three pairs of corresponding sides equal, which means they're congruent—they're the same triangle, just possibly rotated or reflected. The key insight is that congruent triangles have equal corresponding angles. Since the sides match up in a specific order ($AB = DE$, $BC = EF$, $CA = FD$), you can identify which angles correspond to each other and use that correspondence to find $\angle B$ from the given information about $\angle E$.