共50条信息
两圆\(x^{2}+y^{2}+2ax+a^{2}-4=0\)和\(x^{2}+y^{2}-4by-1+4b^{2}=0\)恰有三条公切线,若\(a∈R\),\(b∈R\),且\(ab\neq 0\),则\(\dfrac{1}{{{a}^{2}}}+\dfrac{1}{{{b}^{2}}}\)的最小值为
圆\({{x}^{2}}+{{y}^{2}}-2x=0\)和圆\({{x}^{2}}+{{y}^{2}}+4y=0\)的公切线有且仅有 \((\) \()\)
圆\(x^{2}+y^{2}+4x-4y+7=0\)与圆\(x^{2}+y^{2}-4x+10y+13=0\)的公切线的条数是________.
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