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Geometry. Chapter 1. Lesson (1-1) POINTS, LINES, & PLANES. What are the 3 BASIC UNDEFINED TERMS IN GEOMETRY ? Answer: Point , line, & plane They do not have any shape or size . They are generally defined using examples. Lesson (1-1) POINTS, LINES, & PLANES. A point
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Geometry Chapter 1
Lesson (1-1)POINTS, LINES, & PLANES What are the 3 BASIC UNDEFINED TERMS IN GEOMETRY? Answer: Point, line, & plane They do not have any shape or size. They are generally defined using examples.
Lesson (1-1)POINTS, LINES, & PLANES A point • is a location. • has no shape or size. • is named using one capital letter. EX: A
Lesson (1-1)POINTS, LINES, & PLANES A line: • is made up of infinitely many points. • has no thickness.
Lesson (1-1)POINTS, LINES, & PLANES A line is named 2 ways. 1. Using 2 capital printed letters representing 2 points on the line E D
Lesson (1-1)POINTS, LINES, & PLANES 2. Using a lowercase, cursive letter. line m
Lesson (1-1)POINTS, LINES, & PLANES • A plane: • Is a flat surface made up of points that extends infinitely in all directions. • has no thickness.
Lesson (1-1)POINTS, LINES, & PLANES A plane is named 2 ways. 1.) using 3 capital printed letters representing 3 points that are not all on the same line EX. plane BCD or plane DBC or plane CBD, etc
Lesson (1-1)POINTS, LINES, & PLANES • 2. using 1 capital, cursive letter plane N
Lesson (1-1)POINTS, LINES, & PLANES COLLINEAR POINTS: Points that lie on the same line COPLANAR POINTS: Points that lie on the same plane
Lesson (1-1)POINTS, LINES, & PLANES INTERSECTION: The set of points that 2 or more geometric figures have in common 1.) 2 lines intersect in a ________. In the diagram, line aand line b intersect at point R. point
Lesson (1-1)POINTS, LINES, & PLANES 2.) A line and a plane intersect in _________________________________ ___________________ EX In the first diagram, In the second diagram, line k and plane Bline p lies completely in intersect at point P.plane Q , so their intersection is line p. a point OR the line if the line lies in the plane.
Lesson (1-1)POINTS, LINES, & PLANES line 3.) 2 planes intersect in a. EX
Lesson (1-1)POINTS, LINES, & PLANES POSTULATE OR AXIOM: An accepted statement of fact POSTULATE Through any 2 points there is . EX exactly one line
Lesson (1-1)POINTS, LINES, & PLANES POSTULATE If 2 lines intersect, then they intersect in . EX exactly one point
Lesson (1-1)POINTS, LINES, & PLANES POSTULATE If 2 planes intersect, then they intersect in . exactly one line
Lesson (1-1)POINTS, LINES, & PLANES POSTULATE Through any 3 noncollinear points there is . exactly one plane
Lesson (1-1)POINTS, LINES, & PLANES Assignment: Worksheet Front: #1, 7, 10 – 13, 15, 19 Back: #1, 4, 5, 8, 24, 33, 35, 40, 43
Segments, Rays, Parallel Lines, and Planes Segment: The part of a line consisting of 2 endpoints and all points between them Q P consists of points P and Q and all of the points between them To name a line segment use 2 capital letters and a segment above them.
Segments, Rays, Parallel Lines, and Planes What is the difference between and ? SEGMENT AB is at the right in blue A B LINE AB is at the right in red A B
Segments, Rays, Parallel Lines, and Planes IN CLASS: Front of worksheet #1,7,10-13,15,19 Assignment: Back of worksheet #1,4,5,8,24,33,35
Segments, Rays, Parallel Lines, and Planes Ray: The part of a line consisting of one endpoint and all the points of the line on one side of the endpoint
Segments, Rays, Parallel Lines, and Planes Naming a RAY: FIRST: Name the endpoint. SECOND: Name another point on the line closer to the arrow. THIRD: Write over the letters.
Segments, Rays, Parallel Lines, and Planes Name the rays. EX D N M F is not the same as .
Segments, Rays, Parallel Lines, and Planes Opposite Rays: 2 collinear rays with the same endpoint Opposite rays ALWAYS form a line! C B A
Segments, Rays, Parallel Lines, and Planes and are OPPOSITE RAYS!!! R Q P Together, they make .
Segments, Rays, Parallel Lines, and Planes Let’s do #2 – 6, 14, 17, & 18 front of the worksheet together for practice!
Segments, Rays, Parallel Lines, and Planes Parallel lines: Coplanar lines that do not intersect Give some real life examples of parallel lines.
Segments, Rays, Parallel Lines, and Planes Skew lines: Non-coplanar lines that do not intersect Give some real life examples of skew lines.
Segments, Rays, Parallel Lines, and Planes Parallel Planes: Planes that do not intersect Give some real life examples of parallel planes.
Segments, Rays, Parallel Lines, and Planes Let’s do #8,9, & 21 on the front of the worksheet.
Segments, Rays, Parallel Lines, and Planes Assignment: Do the rest of the back of the worksheet. #2,3,6,7,9-23,25-32,34, 37-39,41,42,44-47 When you have finished this, you should have the front and back of the worksheet completed.
Measuring Segments A B C D E F ‒2 ‒1 ‒4 ‒3 4 3 2 1 0 To find the length of a segment, think RIGHT minus LEFT.
Measuring Segments A B C D E F ‒2 ‒1 ‒3 4 3 2 1 0 ‒4 The length of is F - E or 4 – 2 = 2.
Measuring Segments A B C D E F ‒2 ‒1 ‒4 ‒3 4 3 2 1 0 1. 2. 3. 4.
Measuring Segments A B C D E F ‒2 ‒1 ‒3 4 3 2 1 0 ‒4 Remember, RIGHT MINUS LEFT. 1. DF= 4 – 1 = 3 2. CE= 2 – 0 = 2 3. BC= 0 – (‒1) = 1 4. AE= 2 – (-3) = 5
Measuring Segments When we found the lengths of the segments on the previous slide, notice how we wrote the lengths. 1. DF= 4 – 1 = 3 2. CE= 2 – 0 = 2 3. BC= 0 – (‒1) = 1 4. AE= 2 – (-3) = 5 We wrote = 3 and not = 3. DF
Measuring Segments When we write the length of a segment, we do NOT write “ ― “ over the letters. Find AD & AF. AD = 4 & AF = 7
Measuring Segments Congruent segments Segments with the same length
Measuring Segments A B C D E F ‒2 ‒1 ‒4 ‒3 4 3 2 1 0 is congruent to what other segments on the number line?
Measuring Segments Since all have length 2, they are congruent. The symbol for congruent is ≅ .
Measuring Segments SEGMENT ADDITION POSTULATE If 3 points A, B, and C are collinear, and B is between A and C, then AB + BC = AC A B C
Measuring Segments If 3 points A, B, and C are collinear and B is between A and C, then AB + BC = AC A B C If AB = 5, and BC = 8, then we write…. 5 + 8 = 13… AC = 13
Measuring Segments X, Y, AND Z are collinear and Y lies between X and Z. Sketch a diagram representing this information, and use it to write an equation using the letters X, Y, and Z. Then do the problems on the following slides. X Y Z XY + YZ = XZ
Measuring Segments 1. XY = 5, YZ = 3; Find XZ. X Y Z XY + YZ = XZ 5 + 3 = XZ 8 = XZ
Measuring Segments 2. XY = 4, XZ = 11; Find YZ. XY + YZ = XZ 4 + YZ = 11 YZ = 7
Measuring Segments 3. If XZ = 70, XY = 3a - 2, and YZ = 5a, find the value of a, XY, and YZ. XY + YZ = XZ (3a – 2) + (5a) = 70 8a – 2 = 70 8a = 72 a = 9 XY = 3a - 2 = 3(9) – 2 = 25 YZ = 5a= 5(9) = 45