Oh, dude, the prefix for angle is "angle." It's like when you add "un" to "happy" to make "unhappy," but with angles. So, if you have an angle, you can add the prefix "angle" to it to make it, well, "angle." Easy peasy, right?
'Tri' is a prefix for angle
A prefix for angle is "anti-."
bi- like bicycle, binary, angle bisector, etc.
Tri
It gets its name from the Greek prefix icosa- meaning 20 and suffix -gon which means angle(s).
Triangles are based on the prefix 'tri', meaning three, and the root word 'angle', so the meaning is plain: 'tri-angle' means three angles, which is what a triangle is (a shape with three angles).
Prefix=IN
The prefix for inadequate is in-. The prefix in- means not.
The prefix for include is in-. This prefix means not.
Yes, prefix does have a prefix. The prefix is pur-.
Demi has no prefix; it IS a prefix.
The prefix is in-. This prefix means not.