ANGLES

Corresponding

• Definition: Angles that lie on the same side of the transversal, on the same side of lines r & s.
• Postulate: If two parallel lines are cut by a transversal, then the pairs of corresponding angles are congruent.

ALTERNATE INTERIOR

• Definition: Adjacent angles that lie on the opposite sides of the transversal between r & s.
• Theorem: If two parallel lines are cut by a transversal, then the pairs of alternate interior angles are congruent.

ALTERNATE EXTERIOR

• Definition: Angles that lie on the opposite sides of the transversal, out-side lines r & s.
• Theorem: If two parallel lines are cut by a transversal, then the two pairs of alternate exterior angles are congruent.

SAME-SIDE INTERIOR

• Definition:(consecutive interior angles)- Angles that lie on the same side of the transversal between r & s.
• Theorem: If two parallel lines are cut by a transversal, then the two pairs of same-side interior angles are supplementary.

VERTICAL

• Definition: Two non adjacent or opposite angles.
• Theorem: If two angles are vertical angles then their measures are equal.

COMPLEMENTARY

• Definition: Two angles that add to equal 90°.
• Hint: When the two angles are put together they form a right angle.

SUPPLEMENTARY

• Definition: Two angles that add to equal 180°.
• Hint: When the two angles are put together they form a straight angle.

ADJACENT

• Definition: Two angles that share a vertex and one side.
• Hint: Adjacent angles are two angles put together.

LINEAR PAIRS

• Definition: Two adjacent angles whose non common side form a straight angle.
• Theorem: If two angles from a linear pair, then they are supplementary.

ACUTE

• Definition: An angle whose measure is more than 0° but less than 90°.
• Hint: The acute angle is smaller than the right, obtuse, and straight angles.

RIGHT

• Definition: An angle whose measure is exactly 90°
• Hint: The right angle forms the capital "L" shape.

OBTUSE

• Definition: An angle whose measure is more than 90°, and less than 180°
• Hint: the obtuse angle looks bigger than a right angle but smaller than a straight angle.

STRAIGHT

• Definition: An angle whose measure is exactly 180°.
• Hint: A straight angle forms a straight line or segment.

CONGRUENT

• Definition: Two angles that are the same measure.
• Congruent Complement Theorem: If two angles are complementary to the same angle, then the two angles are congruent.
• Congruent Supplement Theorem: If two angles are supplementary to the same angle, then the two angles are congruent.
• Hint: If two angles are congruent, then one can fit perfectly on top of the other.