Meaning of 見切線 in Japanese

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Definition of 見切線

みる(miru) 【見る ·観る ·視る】

(v1, vt) to see; to look; to watch; to view; to observe
１０ページの５行目をみなさい。
Let's begin with the fifth line on page 10.
to look over; to look on; to assess; to examine; to judge →Related words: 診る
to look after; to keep an eye on; to take care of →Related words: 看る
私も親の面倒とか見られないですね。
I can't look after my parents and such either.
to view (e.g. flowers, movie)
映画を観に行かない？
Would you like to take in a movie?
to try; to try out
もう一度着てみていいですか。
May I put it on again?
to see that...; to find that...

せっせん(sessen) 【切線 ·接線】