1. 2.2 Definition and Biconditional Statements Use definitions and biconditional statements

2. Definition is used to describe In Geometry definitions describe and carry information. Definition of perpendicular lines : lines that form right angle. Here we know that perpendicular lines make right angles

3.  Definition of a perpendicular line to a plane : A line which is perpendicular to every line on the plane at the point of intersection.

4. Classify the angles BAXCDBAXCD

5. How to Write Perpendicular Lines AC BD This means that Line AC is perpendicular to line BD An upside down T means perpendicular

6. Conditional Statement and its Converse A conditional statement and its converse can be combined to make a Biconditional statement Biconditional statement can also be true or false

7. If it is a line, then it contains two points If it contains two points, then it is a line As a biconditional statement It is a line if and only if it contains at least two points if and only if as often written as iff

8. Write as two statements Two angles are complementary if and only if their sum is 90 degrees.

9. Write as two statements Two angles are complementary if and only if their sum is 90 degrees. If two angles are complementary, then their sum is 90 degrees. If the sum of two angles is 90 degrees, then the two angles are complementary

10. Is this biconditional statement true? x 2 ≤ 49 if and only if x ≤ 7

11. Homework Page 82-83 #13 – 31

12. Homework Page 83 – 84 # 32 – 44, 50, 59 - 68