在直角三角形ABD中cos30°=AB:AD
所以 AD长是6√3
在直角三角形ACB中 因为AC=BC 所以是等腰直角三角形
BC²+AC²=AB²
2BC²=108
BC²=54
BC=3√6
如图所示,∠ABD=∠C=90°,AC=BC,∠DAB=30°,AD=12,求BC²的长
如图所示,∠ABD=∠C=90°,AC=BC,∠DAB=30°,AD=12,求BC²的长
数学人气：917 ℃时间：2020-01-28 20:10:55
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