依高中椭圆常识有 2a=2.85,2b=1.93,所以 a=1.425,b=0.965,所以 c=√(a²-b²)=√(1.425²-0.965²)=1.0485 a-c=1.425-1.0485=0.3765
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依高中椭圆常识有 2a=2.85,2b=1.93,所以 a=1.425,b=0.965,所以 c=√(a²-b²)=√(1.425²-0.965²)=1.0485 a-c=1.425-1.0485=0.3765