Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

How should "three coplanar lines intersect" be drawn? Will they form something that looks like an asterisk? Or three lines that somehow form a triangle? Or either interpretation is acceptable?

share|cite|improve this question
Either interpretation is acceptable. – user53153 Feb 2 '13 at 2:49
"three coplanar lines concur" (or, "are concurrent") would unambiguously indicate the asterisk case. – Blue Feb 2 '13 at 3:23
up vote 1 down vote accepted

The asterisk would be more clearly described by "three coplanar lines intersect in a point", and the triangle would be more clearly described by "three coplanar lines intersect pairwise". Without either of these clarifications, the statement is ambiguous and could be interpreted either way, depending on the context.

share|cite|improve this answer
Thank you for all your answers. - Case closed - – user60623 Feb 2 '13 at 4:33
@user60623: That's what the checkmark is for -- if your question has been fully answered, you can click on the checkmark next to the answer that you want to accept as the best answer; this has the effect that the question is no longer marked as unanswered in the system and thus doesn't take up valuable space on the main page. It also gives $15$ points to the answer's author. If you just want to acknowledge an answer you find helpful but don't think it fully resolves the question, you can just upvote it with the up arrow next to it (which gives $10$ points to the author). – joriki Feb 2 '13 at 5:41

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.