Angle an angle with a measure greater than 90º but less than 180º. 2. acute angle a segment, ray or line which divides the angle into two angles of equal measure. 3. bisector of an angle an angle whose measure is greater than zero and less than 90º. 4. right angle lines that intersect to form right angles. 5. obtuse angle formed by two rays that have a common endpoint. 6. perpendicular lines an angle whose measure equals 90º.