Basic Geometric Ideas

New Orleans Geogebra Institute, Jul 18, 2016

Table of Contents

  1. Lines
    1. Slopes and Angles between Lines
    2. Working with Midpoints
  2. Angles
    1. Size of Angle
    2. Alternate Interior Angles
    3. Alternate Exterior Angles
    4. Vertical Angles
  3. Triangles
    1. Sum of Angles of Triangle

1.

Lines

  • 1. Slopes and Angles between Lines
  • 2. Working with Midpoints

1.1.

Slopes and Angles between Lines

How are the slopes of two lines that meet at a 90 degree angle (perpendicular lines) related? Use your mouse or arrow keys to move the point G until the lines are perpendicular.

What is the relationship between the slopes of two lines that are perpendicular?
– Andy Talmadge

1.2.

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2.

Angles

  • 1. Size of Angle
  • 2. Alternate Interior Angles
  • 3. Alternate Exterior Angles
  • 4. Vertical Angles

2.1.

Size of Angle

Explore the size of angles in degrees by moving rays.

Make angles of size 30, 45, 60, 90, 120, 135, 150, 180, 210, 225, 240, 270 degrees.
– Andy Talmadge

2.2.

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2.3.

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2.4.

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3.

Triangles

  • 1. Sum of Angles of Triangle

3.1.

Sum of Angles of Triangle

Graphic to show angles of triangle sum to 180 degrees
– Andy Talmadge

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