1 / 6

1.2 Informal Geometry and Measurement

1.2 Informal Geometry and Measurement. Undefined terms (terms that are described not defined) Point: Represented by a dot Has location, not size Has no dimension Line Infinite set of points Have a quality of “straightness” One-dimensional Represented symbolically by  (Fig 1.9 p. 10)

thammond
Télécharger la présentation

1.2 Informal Geometry and Measurement

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 1.2 Informal Geometry and Measurement • Undefined terms (terms that are described not defined) • Point: • Represented by a dot • Has location, not size • Has no dimension • Line • Infinite set of points • Have a quality of “straightness” • One-dimensional • Represented symbolically by  (Fig 1.9 p. 10) • Collinear: 3 points on the same line __ • Line segment: part of a line between two points: BC • Midpoint: a point equal distance from the ends of a line segment • Plane • Two-dimensional • Infinite number of points and infinite number of lines • Coplanar points: lie in the same plane.

  2. Measuring line segments • Line segment is part of a line consisting of 2 distinct points. • We label a line or line segment by its endpoints. • Fig 1.11 & 1.9 p. 11 • Tool: Ruler • Metric conversion: 1 inch = 2.54 cm

  3. Measuring angles • Tool: Protractor • Angle’s size depends on the amount of opening between its sides. • Unit of measure: degree • Naming Angles: (Fig 1.10 p. 11) • Where the two sides meet is the vertex. • The vertex is always in the middle with the point on each side surrounding it. ABC . • Ex 4 – 5 p. 14-15

  4. Relationships • Parallel lines, never meet. Figure 1.19 p. 14 • Congruent angles have angles of equal measure. • Bisect an angle means to cut the angle in half. • Straight angle has 180 and is a straight line. • Intersecting lines have a point in common. • Perpendicular lines intercept to form two congruent angles. Each is 90. • Right angles are 90.

  5. CirclesFig 1.25 p. 15 • Set of all points in a plane that are at a given distance from a particular point (center) • Arc is any part of the circle between any of its two points. • Radius is any line segment joining the center to a point on the circle. We use a Compass (fig. 1.24) to draw circles or parts of circles (arcs)

  6. Constructions • Tools: • Compass • Straight edge. • Constructions: use ONLY these two tools: • Construct a segment congruent to a given line segment AB. P. 16, Fig. 1.26 • Construct the midpoint M of a given line segment AB. • P. 16, Fig 1.27

More Related