I'm pretty sure all triangles measure 180 degrees because they have three angles that are either acute, right, or obtuse angles and the triangle has to be either an equilateral, iscoceles, or scalene triangle.
NO they are not they all have the same measure but are not all comgruent
you measure all the sides
Congruent triangles are the same because all three sides measure the same length.
Yes
No, the interior angles of a triangle measure 180° altogether.
Not necessarily. You have described "similar" triangles. If you also know that any of the lengths of sides are of equal measure in addition to three angles (congruent), then the lengths of all of the sides are of equal measure. But with what you have given, consider, for example, two equilateral triangles, both have all angles equal to 60 degrees (satisfying the condition in your question). One of the triangles could have sides length 1 and the other with sides all of length 2.
Three triangles
Three
If all of the diagonals are drawn from a vertex of an octagon, how many triangles are formed
All isosceles triangles are not equilateral triangles
3 triangles
5 triangles are formed.