How to know if an equation is false, true, or an open scentence

Well it is true if the problem is the right with the right answer.  If not you have a false eqaution.

To know when a equation is false, it is simply incorrect. When a equation is true, it will be correct. An open sentence is a statement which contains a variable, and becomes either true or false, depending on the value that replaces the variable. Hope this helps!

One unique triangle, because those angles add up to 180, and that's how many degrees there are in one triangle.