题目内容
如图,△ABC中,∠A=45°,点D、E分别在AB、AC上,则∠1+∠2的大小为( )

A.225° | B.135° | C.180° | D.315° |

∵∠1=∠A+∠ADE,∠2=∠A+∠AED,
∴∠1+∠2
=∠A+∠ADE+∠A+∠AED
=∠A+(∠ADE+∠A+∠AED)
=45°+180°
=225°.
故选A.
∴∠1+∠2
=∠A+∠ADE+∠A+∠AED
=∠A+(∠ADE+∠A+∠AED)
=45°+180°
=225°.
故选A.

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