[anthonyIPH]

I had to reason with my brain before it would accept it as a triangle. It has 3 sides and 3 corners so...

[bigstrat2003]

It's one of those things where it's technically correct but the headline is misleading. When you say "a triangle" without any qualification as the headline does, people are going to interpret that as a good old fashioned triangle. Using the term without clarification that you mean spherical geometry is kind of underhanded writing, imo.

[cwillu]

The title attribute of the article is <title>A hyperbolic triangle with three cusps</title>

[eru]

It's a mild form of clickbait.