△ABC中,AB=AC,CD为AB上的高,且△ADC为等腰三角形,则∠BCD等于( ) A.67.5° B.22.5° C.45° D.67.5°或22.5°
△ABC中,AB=AC,CD为AB上的高,且△ADC为等腰三角形,则∠BCD等于( )
A. 67.5°
B. 22.5°
C. 45°
D. 67.5°或22.5°
A. 67.5°
B. 22.5°
C. 45°
D. 67.5°或22.5°
数学人气:811 ℃时间:2020-02-03 00:07:00
优质解答
①如右图所示,CD在△ABC内部,∵AB=AC,CD为AB上的高,∴∠B=∠ACB,∠CDB=90°,又∵△ADC是等腰三角形,∴∠DAC=∠DCA=45°,∴∠B=∠ACB=12(180°-45°)=67.5°,∴∠BCD=∠ACB-ACD=67.5°-45°=22.5°;②如...
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