Presentation on theme: "Unit 1 Points, Lines, Planes, and Angles"— Presentation transcript:
1Unit 1 Points, Lines, Planes, and Angles Pre-AP GeometryUnit 1Points, Lines, Planes, and Angles
2About APAP can change your life. Through college-level AP courses, you enter a universe of knowledge that might otherwise remain unexplored in high school. Through AP Exams, you have the opportunity to earn credit or advanced standing at most of the nation's colleges and universities.
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6Broaden Your Intellectual Horizons Explore the world from a variety of perspectives, most importantly your own.Study subjects in greater depth and detail.Assume the responsibility of reasoning, analyzing, and understanding for yourself.
7Introduction to Geometry (Greek γεωμετρία; geo = earth, metria = measure)is a part of mathematics concerned with questions of size, shape, and relative position of figures and with properties of space.Geometry is one of the oldest sciences.
8Introduction to Geometry Geometry is a type of math used to measure things that are impossible to measure with devices. For example, no one has been able take a tape measure around the earth, yet we are pretty confident that the circumference of the planet at the equator is 24, miles. The first known case of calculating the distance around the earth was done by Eratosthenes around 240 BC.
9Introduction to Geometry The study of Geometry includes proofs. Proofs are not unique to Geometry. They could have been done in Algebra or delayed until Calculus. The reason that high school geometry almost always spends a lot of time with proofs is that the first great Geometry textbook, "The Elements," was written by Euclid, exclusively with proofs.
10Introduction to Geometry This course, for the most part, is based on Euclidean geometry. "Euclidean" (or "elementary") refers to the book "The Elements" written over 2,000 years ago by a man named Euclid.
11Introduction to Geometry Euclid started with some basic concepts. He built upon those concepts to create more and more concepts. His structure and method influence the way that geometry is taught today.
12Introduction to Geometry This course will include more than just facts about geometric objects; the ability to "prove" that a particular answer is correct using logic and reason is the most important part of this course.
13Basic FiguresPointA point is a geometric element that has position but no dimensions and is used to define an exact location in space.A point has no volume, area, or length, making it a zero dimensional object.A point is defined by its coordinates.
14Basic FiguresLineA line can be described as an ideal zero-width, infinitely long, perfectly straight curve (the term curve in mathematics includes "straight curves") containing an infinite number of points.In Euclidean geometry, exactly one line can be found that passes through any two points.
15Basic FiguresEquidistant - equally distant from any two or more points.
16Suppose that you and a friend are partners in a game in which you must locate various clues to win. You are told to pick up your next clue at a point that:Is as far from the fountain as from the oak treeand2. Is 10 m from the telephone pole.You locate X, which satisfies both requirements, but grumble because there simply isn’t any clue tobe found at X.Is there another location that satisfies both requirements?Basic Figures10mXEqual distancesDiscussion in GSP
17Review QuizWhich language does the word “geometry” come from and what does it mean?What is the circumference of the Earth at the equator? (exact value is preferred, but the nearest 1000 is acceptable)Who wrote the book “The Elements”?Which geometric element has dimensions of zero?How many points does it take to define a line?
19Points, Lines and Planes Lesson 1.2Pre-AP Geometry19
20Points, Lines, and Planes The three most basic figures in geometry are points, lines, and planes. This lesson illustrates how these three basic figures relate to one another.20
21Objectives Use the undefined terms point, line, and plane. Draw representations of points, lines, and planes.Use the terms collinear, coplanar, and intersection.21
22VocabularyPointA geometric element that has position but no dimension. A point is defined by its coordinates. Symbol: · ALineA line can be described as an ideal zero-width, infinitely long, perfectly straight curve containing an infinite number of points.Symbol:(The term curve in mathematics includes "straight curves")22
23VocabularyPlane A plane is a two-dimensional surface that is perfectly flat, is infinitely vast, and infinitesimally thin. Undefined term A term, such as point, line, plane, and space, that is accepted without definition.23
24VocabularySpace The set of all points. The unlimited area which extends in all directions and within which all things exist. Intersect To meet or cross at a point.24
25Vocabulary Collinear Lying on the same straight line. Collinear points lie along a straight line.Any two points are always collinear.CoplanarLying in the same plane.A set of points in space is coplanar if the points all lie in the same plane.Note: Collinear points are automatically coplanar, but coplanar points are not necessarily collinear.25
26PointsThings that we can use to represent a point: a marble26
27LinesThings that we can use to represent a line: a taut piece of string27
28PlaneThings that we can use to represent a plane: a sheet of paper a poster board28
29Intersecting PlanesThings that we can use to represent intersecting planes: the sides of a cardboard box29
30Practice Quiz - True or False ends at P.Point S is on an infinite number of lines.A plane has no thickness.Collinear points are coplanar.Planes have edges.Two planes intersect in a line segment.Two intersecting lines meet in exactly one point.Points have no size.30
31Problem Set 1.2 Written Exercises p.7: # 2 – 26 even, 27 - 36 31
32Lesson 1.3: Segments, Rays, and Distance Pre-AP Geometry
33Points, Lines, and Planes Line SegmentTwo points (called the endpoints) and all the points between them that are collinear with those two pointsNamed line segment AB, AB, or BAline AB segment AB A B A BAlways name a segment using the endpoints.33
34Length of a segmentLength of BC is stated as BC. It is the distance between points B and C.On a number line, length of a segment is found by subtracting the coordinates of the endpoints.On a coordinate plane, length of a segment is found using the distance formula D =
35Examples Find the length between 5 and -3 on the number line Find the distance of segment AB if A(-3, 5) and B(2, -7)
36Postulates Postulate: statement that is accepted without proof Segment Addition PostulateIf B is between A and C, then AB + BC = ACRuler PostulateThe points on a line can be paired with the real numbers in such a way that any two points can have the coordinates 0 and 1Once a coordinate system has been chosen in this way, the distance between any two points equals the absolute value of the difference of their coordinates.
38Segment Length termsCongruent- two objects that have the same size and shape. We use the symbol ≅ to show that two objects are congruent.Congruent segments- two segments with equal lengths.Example: DE ≅ FGMidpoint of a segment: a point that divides a segment into two congruent segments.Midpoint formula: M = ( )Segment bisector: A line, segment, ray, or plane which intersects a segment at its midpoint.
39Points, Lines, and Planes RayPart of a line that starts at a point and extends infinitely in one direction.Initial PointStarting point for a ray.Ray CD, or CD, is part of CD that contains point C and all points on line CD that are on the same side as of C as D“It begins at C and goes through D and on forever”
40Points, Lines, and Planes Opposite RaysIf C is between A and B, then CA and CB are opposite rays.Together they make a line.Use yarn and have students go to front and show this.ABC40
43Parts of an angle Sides of an angle are made up of rays The rays meet at a point called the vertexvertexsides
44Naming an angleAn angle can be named by the vertex, by the 3 points on the angle: the side, the vertex and the other side, or a number inside the angle.The angle can be named ∠GHI, ∠IHG, ∠H, or ∠1GI1H
45Classifying anglesAcute angle: Angle measuring greater than 0° and less than 90°.Obtuse angle: Angle measuring greater than 90° and less than 180°Right angle: An angle measuring exactly 90°Straight angle: An angle measuring exactly 180°
46Angle Postulates Protractor Postulate: On AB in a given plane, choose any point O between A and B. Consider OA and OB and all the rays that can be drawn from O on one side of AB. These rays can be paired with real numbers from 0 to 180 in a way such that:a. OA is paired with 0, and OB with 180b. If OP is paired with x, and OQ with y, the m∠POQ = │x - y │Angle addition postulate:-If B lies on the interior of ∠AOC, then m ∠AOB + m∠BOC = m∠AOC-If ∠AOC is a straight angle, then m∠AOB+m ∠BOC = 180.
47Angle Vocabulary Congruent Angles Adjacent angles Angle bisector Two angles with equal measuresAdjacent anglesAngles which share a vertex and a common side, but no common interior pointsAngle bisectorA ray which divides an angle into two congruent, adjacent angles
48Congruence symbols and drawing conclusions Do not assume anything in geometry. Just because two segments look equal does not mean that they are.
49Postulates and Theorems Relating Points, Lines, and Planes Lesson 1.5Pre-AP Geometry49
50Postulates A point is defined by its location. A line contains at least two points.A plane contains at least three points not all in one line.Space contains at least four points not all in one plane.50
51PostulatesThrough any two points there is exactly one line. Through any three points there is at least one plane and through any three non-collinear points there is exactly one plane. If two points are in a plane, then the line that contains the point is in that plane. If two planes intersect, then their intersection is a line.51
52TheoremIf two lines intersect, then they intersect in exactly one point.52
53TheoremThrough a line and a point not in the line there is exactly one plane.53
54TheoremIf two lines intersect, then exactly one plane contains the lines.54
55Review Quiz – True or False A given triangle can lie in more than one plane.Any two points are collinear.Two planes can intersect in only one point.Two lines can intersect in two points.55
56Review Quiz – True or False A given triangle can lie in more than one plane. False. Through a line and a point not in the line there is exactly one plane.Any two points are collinear. True.Two planes can intersect in only one point. False. If two planes intersect, then they intersection is a line.Two lines can intersect in two points. False. If two lines intersect, then they intersect in exactly one point.56
57Problem Set 1.5 Written Exercises p.25: # 1 –20 57