
如图,在△ABC中,D是AC上一点,AB=AC,且AD=BD=BC,则∠A=? ,∠C?∠ABC?
2个回答
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设∠A=x
∵AD=BD
∴∠ABD=∠A=x
∵BD=BC
∴∠C=∠BDC=∠A+∠ABD=2x
∵AB=AC
∴∠ABC=∠C=2x
∠A+∠ABC+∠C=180°
x+2x+2x=180° x=36°
∴∠A=36° ∠C=∠ABC=72°
∵AD=BD
∴∠ABD=∠A=x
∵BD=BC
∴∠C=∠BDC=∠A+∠ABD=2x
∵AB=AC
∴∠ABC=∠C=2x
∠A+∠ABC+∠C=180°
x+2x+2x=180° x=36°
∴∠A=36° ∠C=∠ABC=72°
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