# Graphing Prevents Overthinking

Geometry Level 2

There are four lines that are tangent to both circles
${ x }^{ 2 }+{ y }^{ 2 }=1 \quad \text{ and } \quad ({ x }-6)^{ 2 }+{ y }^{ 2 }=4.$

What is the sum of the slopes of these four lines?

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