8-1

1. 8-1 Building Blocks of Geometry Course 1 Warm Up Problem of the Day Lesson Presentation

2. 2 3 1 4 2 5 3 1 2 Warm Up Solve 1.x + 1 = 5 2. 2 = 2x 3.x – 7 = 6 4. = 1 3 1 2 2 3 1 3 14 4 5 x 3

3. Problem of the Day Draw a clock face that includes the numerals 1–12. Draw two lines that do not intersect and that separate the clock face into three parts so that the sums of the numbers on each part are the same.

4. Learn to describe figures by using the terms of geometry.

5. Vocabulary point line plane line segment ray

6. A point is an exact location. P point P, P A point is named by a capital letter. A line is a straight path that line AB, AB, extends without end in A B line BA, BA opposite directions. A line is named by two points on the line. M A plane is a flat surface that plane LMN, extends without end in all plane MLN, directions. plane NLM A plane is named by three points on the plane that are not on the same line. L N The building blocks of geometry are points, lines, and planes.

7. Q P R M N PR and NR You can also write RP and RN. Additional Example 1: Identifying Points, Lines, and Planes Use the diagram to name the geometric figure. A. three points M, N, and P Five points are labeled: points M, N, P, Q, and R. B. two lines

8. Point R is a point on PR and NR. Q P R M N Additional Example 1: Identifying Points, Lines, and Planes Use the diagram to name the geometric figure. C. a point shared by two lines point R D. a plane plane QRM Use any three points in the plane that are not on the same line. Write the three points in any order.

9. V U W T S UW and SW You can also write WU and WS. Check It Out: Example 1 Use the diagram to name the geometric figure. A. three points S, T, and U Five points are labeled: points S, T, U, V, and W. B. two lines

10. Point W is a point on WS and WU. V U W T S Check It Out: Example 1 Use the diagram to name the geometric figure. C. a point shared by two lines point W D. a plane plane VUT Use any three points in the plane that are not on the same line. Write the three points in any order.

11. A line segment is line segment XY, XY, made of two endpoints Y line segment YX, YX and all the points between X the endpoints. A line segment is named by its endpoints. A rayhas one endpoint. ray JK, JK From the endpoint, the ray J K extends without end in one direction only. A ray is named by its endpoint first followed by another point on the ray.

12. B A C AB, BC, and AC You can also write BA, CB, and CA. AB, BC, and AC You can also write BA, CB, and CA. Additional Example 2: Identifying Line Segments and Rays Use the diagram to give a possible name to the figure. A. three different line segments B. three ways to name the line

13. B AB, AC, BC, CB, CA, and BA A C AC Additional Example 2: Identifying Line Segments and Rays Use the diagram to give a possible name to the figure. C. six rays D. another name for ray AB A is still the endpoint. C is another point on the ray.

14. D E F DE, EF, and DF You can also write ED, FE, and FD. DE, EF, and DF You can also write ED, FE, and FD. Check It Out: Example 2 Use the diagram to give a possible name to the figure. A. three different line segments B. three ways to name the line

15. D DE, EF, DF, FE, FD, and ED E F DF Check It Out: Example 2 Use the diagram to give a possible name to the figure. C. six rays D. another name for ray DE D is still the endpoint. F is another point on the ray.

16. Possible answer: AD, CE Lesson Quiz Use the diagram to name each geometric figure. 1. three points 2. two lines 3. a point shared by a line and a ray 4. a plane Possible answer: A, B, C Possible answer: F Possible answer: plane AEC