Download Discovering Geometry Day 3

Discovering Geometry
Day 3
1.3 What’s a Widget
o Daily Openers
o Check homework
1.3 What’s a Widget
counterexample – an example that shows a conjecture to be incorrect.
CREATING A GOOD DEFINITION
1. Classify your term.
2. Differentiate your term.
3. Test your definition by looking for a counterexample.
 Define parallel lines.
parallel lines – coplanar lines that do not intersect.
perpendicular lines – lines that intersect to form four 90° angles.
skew lines – lines that do not lie in the same plane.
 On pages 49–50, define the terms in bold.
right angle – an angle that measures 90°.
acute angle – an angle that measures between 0° and 90°.
obtuse angle – an angle that measures between 90° and 180°.
complementary angles – two angles whose measures sum to 90°.
supplementary angles – two angles whose measures sum to 180°.
vertical angles – two angles across from each other, formed when two lines intersect.
linear pair of angles – two angles with a common side that are supplementary.
Homework – pages 51–53 #1–34 all
Daily Openers – 1. Simplify: 7 500
2. Simplify: 2
5
6
3. What are the three undefined terms?
4. Solve: 13  4x  1
5. Solve:
6 x  8 y  62
4 x  5x  0