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Geometry (Lines) SOL 4.14, 4.15, 4.16. lines, segments, rays, points, angles, intersecting, parallel, & perpendicular. 4.14 The student will investigate and describe the relationships between and among points, lines, line segments, and rays. 4.15 The student will
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Geometry (Lines) SOL 4.14, 4.15, 4.16 lines, segments, rays, points, angles, intersecting, parallel, & perpendicular • 4.14 The student will investigate and describe the relationships between and among points, lines, line segments, and rays. • 4.15 The student will • a) identify and draw representations of points, lines, line segments, rays, and angles, using a straightedge or ruler; and • b) describe the path of shortest distance between two points on a flat surface. • 4.16 The student will identify and draw representations of lines that illustrate intersection, parallelism, and perpendicularity.
Point • “A point is an exact location in space. • It has no length or width.” • Points have names; represented with a Capital Letter. • Example: A
Lines a • “A line is a collection of points going on and on infinitely in both directions. It has no endpoints.” • A straight line that continues forever • It can go • Vertically • Horizontally • Obliquely (diagonally) • It is identified because it has arrows on the ends. • It is named by “a single lower case letter”. • Example: “line a”
B C D A Line Segment • “A line segment is part of a line. It has two endpoints and includes all the points between those endpoints. “ • A straight line that stops • It can go • Vertically • Horizontally • Obliquely (diagonally) • It is identified by points at the ends • It is named by the Capital Letter End Points • Example: “line segment AB” or “line segment AD”
C B A Ray • “A ray is part of a line. It has one endpoint and continues on and on in one direction.” • A straight line that stops on one end and keeps going on the other. • It can go • Vertically • Horizontally • Obliquely (diagonally) • It is identified by a point at one end and an arrow at the other. • It can be named by saying the endpoint first and then say the name of one other point on the ray. • Example: “Ray AC” or “Ray AB”
Angles C A B • Two Rays That Have the Same Endpoint Form an Angle. This Endpoint Is Called the Vertex. • Angles Are Found Wherever Lines and Line Segments Intersect.
C A A B 1 Angles • An Angle Can Be Named in Three Different Ways by Using • Three Letters to Name, in This Order, Example: “Angle BAC” • A Point on One Ray, • The Vertex, and • A Point on the Other Ray; • One Letter at the Vertex; “Angle A” • Or a Number Written Inside the Rays of the Angle. Example: “Angle 1”
C C A A B B Angles • There are 3 types of angles • Acute Angle: Smaller than 90 degree opening • Obtuse Angle: Larger than 90 degree opening • Right Angle: 90 degree opening C A B C A B
D C B A E Intersecting Lines • “Intersecting lines are lines that cross and have one point in common.” • Example: “Line AC intersects Line DE at Point B”
Perpendicular Lines • “Perpendicular lines are special intersecting lines that form right angles (square corners) where they intersect.”
Parallel Lines • “Parallel lines are lines that lie on the same flat surface (plane) and never cross. • Parallel lines are always the same distance apart and do not share any points.” • Example: “Line AB is Parallel to Line CD” C D A B
a B C D A A C A B C B A Name That Line! 1. 3. 5. 2. 4.
C A B C C A B A B Name That Angle! 7. 6. 8.
B D C A E Name The Type of Lines! 11. 9. 10.
Now, Draw Your Own Lines. • Point • Line • Line Segment • Ray • Angles • Acute • Obtuse • Right • Intersecting Lines • Perpendicular Lines • Parallel Lines