It would be 11 if I’m reading this right
Hello,
No a triangle with these angles are not unique. This is because every triangle is supposed to have 180 degrees, just like this one.
Have a great day!
The first and the second and the last one
No
A regular polygon has interior angles that are all equivalent. Because the interior angles of a polygon must add up to 360 degrees and since 55 cannot evenly go into 360, it is not possible for all the interior angles to be 55 degrees.