FTCE General Knowledge Math Practice Test

Which term describes an angle whose measure is greater than 90 degrees but less than 180 degrees?

1. Straight angle

2. Complementary angles

3. Obtuse angle

4. Acute angle

The correct answer is: Obtuse angle

An angle that measures greater than 90 degrees but less than 180 degrees is classified as an obtuse angle. This type of angle is characterized by being wider than a right angle, which is exactly 90 degrees, but not as wide as a straight angle, which measures 180 degrees. Understanding the definitions of the different types of angles is key in geometry. For context, a straight angle is defined as one that measures exactly 180 degrees, formed by two rays pointing in opposite directions. Complementary angles are pairs of angles that sum up to 90 degrees, while acute angles measure less than 90 degrees. Thus, the definition of an obtuse angle fits perfectly within the specified range of greater than 90 degrees and less than 180 degrees. Recognizing these classifications helps in identifying and working with angles effectively in mathematical problems.