Question

如图,已知在三角形ABc中,AB=Ac,点D、E分别在Ac、AB上,且Bc=BD=DE=EA,求角A的度数.

Answer 1

∵AB=AC,BC=BD=ED=EA,

∴∠ABC=∠C,∠BCD=∠BDC,∠DBE=∠DEB,∠A=∠EDA,

∴∠C=3∠A=∠ABC,

∵∠ABC+∠C+∠A=180°,

∴7∠A=180°,

∴∠A= (180/7)°