若A是不等边△ABC中最小的内角,且coxαA=a+1/a-1,则实数a的范围
人气:481 ℃ 时间:2020-01-28 15:33:15
解答
若A是不等边△ABC中最小的内角,且cosA=(a+1)/(a-1),则实数a的范围
0<A<60°
1/2<cosA<1
1/2<(a+1)/(a-1)<1
-1/2<2/(a-1)<0
a<-3
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