I don't know why exactly, but the misuse of math terms drives me up the wall, as anyone who's heard me complain about the phrase "one-dimensional characters" can attest. The most recent term to attract my ire is the ol' love triangle, which seldom is ever a true triangle.
Most people think of a love triangle as being between three people where one individual has to choose between two others of the opposite gender. There are three people, so that's where the triangle comes into play since we all know a triangle has three points and three sides.
By way of example, we have this here Twilight thing that I hear was popular many moons ago where below stone-faced girl must choose between the pale male with no personality and the tan one with just as little personality, but more abs.
So let's chart that out with the red lines indicating the flow of affection between all involved. It should look a little something like this:
You'll probably note the lack of a connecting side up there at the top, and that's because there's no love flowing between our two males. So yeah, not an actual triangle and more of a big V. It's not until we add some sexual attraction between our two male leads that we both make a true triangle and fulfill the climax of countless fan-fic stories littering the internet.
Now that is an actual love triangle, which shows if you're going to use the term, you better have some sort of homosexual potential going on. Otherwise, yeah, just the big V.
I should probably note the inverse of this can occur, with the male at the bottom and two women at the top. Also, three women or three men fit the bill just as well. But no matter what, you're going to need some same-sex attraction going on in your love triangle to make t true.
And no, that's not just my personal opinion; that's just math.