Answer: Acute angle: An angle whose measure is less than 90 degrees. The following is an acute angle.
Right angle: An angle whose measure is 90 degrees. The following is a right angle.
Obtuse angle: An angle whose measure is bigger than 90 degrees but less than 180 degrees. Thus, it is between 90 degrees and 180 degrees. The following is an obtuse angle.
Straight angle : An angle whose measure is 180 degrees. Thus, a straight angle look like a straight line. The following is a straight angle.
Explanation: