It is: 180 degrees
An obtuse angle
A reflex angle is between 180 and 360 degrees
It is an obtuse angle. If it is between 90 degrees and 180 degrees it is obtuse but if it is over 180 it is reflex.
An angle greater than 90 but less than 180 degrees is an obtuse angle.
Straight angle
An angle above 90 but less than 180 degrees is an obtuse angle An angle above 180 degrees is a reflex angle
The last major kind of angle is the straight angle. A straight angle is an angle that measures exactly 180 degrees.
There isn't a specific name for 45 degrees, like when 90 degree angle is called a "right angle". However, there is a general term for any angle less than 90 degrees - "acute angle". Here's a full list: < 90 degrees = acute 90 degrees = right angle between 90 & 180 degrees = obtuse 180 degrees = straight line between 180 & 360 degrees = reflex 360 deg = revolution (because it turns in a complete circle)
Their is not an that is 180 degrees. This would only make a line.
That is a straight angle.
Half of a revolution of a circle is 180 degrees and its angles added together are supplementary.