you use a protracter and then if it is above 90 it is oubtuse if it is 90 it is a right angle if it is less then 90 it is a acute and last but not least if it was180 it is also an straight angle
it depends on how many degrees it is. an angle over 90 degrees is an obtuse angle, an angle 90 degrees exactly is a right angle, an angle under 90 degrees is an acute angle, and an angle exact 180 degrees is a straight angle.
