As shown in Figure 1, ab ∥ CD, try to guess the relationship between ∠ bed and ∠ B, ∠ D? Please explain the reason
This method is better than parallel lines
Extend be to Cd in M,
Because ab ‖ CD
Therefore, BMD = B
Because ∠ BMD + D + Med = 180
∠BED+∠MED=180
Therefore, BMD + D = ∠ bed
That is, B + D = bed
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