what's an example of a 2 dimensional triangle?

Good question. I’m doing the difference (in degrees) between jupiter and mars. Sure going to need that in a flower shop…

ANY and EVERY triangle, circle, square, whatever, that you draw on a piece of paper is a two-dimensional figure. (I’m ignoring the height of the pencil mark on the paper.)

A two SIDED triangle doesn’t exist. (Except in the form of a degenerate triangle - where - on a plane - the length of the two shorter sides EXACTLY equal the length of the third side - t looks like a straight line. And even then it still has 3 sides.)

A triangle drawn on a ball or a globe is a three dimensional triangle.

like an equilateral? are you just trying to make a point? well I guess if you’re actually going to use math (like viki said) then it would be helpful to know the basics… architecture, engineering, surveyors, computer programmers, advertisers, etc etc (if you want lists of careers that use math and the specific math topics you’ll find them here http://www.xpmath.com/careers/topics.php)

Equilateral, iscoceles, scalene, right angled… there’s a few.

Maths is applied in loads of different situations in everyday life, and yes, most of us won’t end up using the more complex stuff. However, you need pretty good maths skills to balance books and manage payroll in your own business, Or how to draw an equilateral triangle if you’re doing artwork. Keep an open mind, you never know when you might need this stuff.