際際滷

際際滷Share a Scribd company logo
Section 2.2
Also includes perpendicular and parallel lines
Perpendicular and Parallel
 Perpendicular lines intersect to form a right angle

 A line that is perpendicular to a plane is perpendicular
  to every line in that plane that it intersects

 Definitions, such as these, are meant to be interpreted
  in both directions.

 For example, the first definition could be written
  Two lines that form right angles are perpendicular
Biconditional Statements
 Like definitions, biconditional statements can be
  interpreted in both directions
 They are written in the form:

  <1st statement> if and only if <2nd statement>

 If and only if is often abbreviated iff

 One can make a biconditional statement if the
  conditional statement and its converse are both true
  (or both false, but why would you do that)
Reference
 McDougal Littel: Geometry, Section 2.2

More Related Content

Geo 2.2

  • 1. Section 2.2 Also includes perpendicular and parallel lines
  • 2. Perpendicular and Parallel Perpendicular lines intersect to form a right angle A line that is perpendicular to a plane is perpendicular to every line in that plane that it intersects Definitions, such as these, are meant to be interpreted in both directions. For example, the first definition could be written Two lines that form right angles are perpendicular
  • 3. Biconditional Statements Like definitions, biconditional statements can be interpreted in both directions They are written in the form: <1st statement> if and only if <2nd statement> If and only if is often abbreviated iff One can make a biconditional statement if the conditional statement and its converse are both true (or both false, but why would you do that)
  • 4. Reference McDougal Littel: Geometry, Section 2.2