Download Geometry Honors Section 1.3 Handout Collinearity, Betweenness

Geometry Honors
Section 1.3 Handout
Collinearity, Betweenness, Assumptions
Objectives
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Determine whether points are collinear or noncollinear
Recognize whether a point is between two others
Know and apply the Triangle Inequality
Create a list of what can and what cannot be assumed from a geometric figure
Notes
Collinearity
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Three points are collinear if they are all on the same line (the line does not need to be drawn)
Draw examples of three collinear points and three noncollinear points below
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Can two points be noncollinear?
Betweenness
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A point can only be between two other points if all three are collinear
We can say B is between A and C if 1) A, B, and C are collinear, 2) ______ < ______ and 3)
______ < ______
Triangle Inequality
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What can be concluded about the lengths of the sides of any triangle?
Assumptions
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You can assume:
o Lines are straight
o Points on the same line are collinear
o Betweenness of points
o Relative position of points (left, right, above, etc.)
You should not assume (unless otherwise indicated):
o Measures of angles
o Congruent segments and angles
o Relative sizes of segments and angles
Checkpoint 1: What can you and can you not assume from the following diagram?
DMS and Decimal Degrees
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Write down what you remember about the relationship between degrees, minutes, and seconds:
Example 1: Convert 36°12’30” into decimal degrees. Round to the three decimal places.
Example 2: Convert 14.356° to DMS.
Checkpoint 2:
1. Convert 72°44’20” into decimal degrees.
2. Convert 3.196° into DMS.