滴16 题,

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滴16 题,
滴16 题,
 

滴16 题,
连接AD,则
∠E+∠F
=∠AME
=∠MAD+∠MDA,
于是,
∠A+∠B+∠C+∠D+∠E+∠F
=∠A+∠B+∠C+∠D+∠MAD+∠MDA
=∠A+∠MAD+∠B+∠C+∠D+∠MDA
=∠BAD+∠B+∠C+∠CDA
=四边形ABCD的内角和
=360°
即∠A+∠B+∠C+∠D+∠E+∠F的度数为360°.