Talk:Line–sphere intersection
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Sign Flip
[edit]Oops, meant to comment properly on my undo, but hit enter and accidentally did the undo without explanation. But anyway, the signs were definitely correct before. The minus in front of the 4 flips the sign of the r^2 when you expand it. — Preceding unsigned comment added by 174.7.100.16 (talk) 20:46, 16 July 2017 (UTC)