LESSON 2: Angles

Forms of Angles

1. Acute angle is an angle whose measure is less than 90°.

2. Obtuse angle is an angle whose measure is more that 90° and less than 180°.

3. Right angle is an angle that measure exactly 90°.

4. Straight angle is an angle that measures exactly 180°.

5. Reflex angle is an angle whose measure is more than 180° but less than 360°.

6. Circular angle is an angle that measures exactly 360°.

Terms

1. Complementary angles are two angles whose sum is 90°. 

2. Supplementary angles are two angles whose sum is 180°.

3. Interior and exterior angles are the angles formed by cutiing two parallel lines with a transversal line.

4. Alternate interior angles are a pair of nonadjacent interior angles on opposite sides of the transversal. Alternate interior angles are congruent. 

5. Corresponding angles have the same position with respect to their lines and the transversal. Corresponding angles are congruent.