1. 8-1 Building Blocks of Geometry

2. 8-1 Building Blocks of Geometry Warm Up Solve. 1. -373 – 89 2. 47 – 62 3. 15 x 2/3 4. √16 x √4 -462 -15 10 8

3. 8-1 Building Blocks of Geometry Today’s Goal: Learn to identify and describe geometric figures.

4. 8-1 Building Blocks of Geometry Vocabulary point line plane ray line segment congruent

5. 8-1 Building Blocks of Geometry A point is an exact location. It is usually represented as a dot, but it has no size at all. A point A Use a capital letter to name a point. A line is a straight path that extends without end in opposite directions. A number line is an example of a line. Helpful Hint XY, or YX Use two points on the line X Y

6. 8-1 Building Blocks of Geometry A plane is a Flat surface that Has no thickness and extends forever. plane QRS Use three points in any order, not on the same line, to name a plane. A coordinate plane is an example of a plane. Helpful Hint Q R S

7. 8-1 Building Blocks of Geometry Identify the figures in the diagram. Identifying Points, Lines, and Planes D E F A. three points B. two lines C. a plane D, E, and F DE, DF plane DEF Choose any two points on a line to name the line. Choose any three points, not on the same line, in any order.

8. 8-1 Building Blocks of Geometry Check It Out: Example 1 H I A. four points B. two lines C. a plane H, G, I, and F IH, HF plane IGF Identify the figures in the diagram. G Choose any two points on a line to name the line. Choose any three points, not on the same line, in any order. F

9. 8-1 Building Blocks of Geometry A ray is a part of a line. It has one endpoint and extends forever one direction. GH Name the endpoint first when naming a ray. A line segment is part of a line or a ray that extends from one endpoint to another. LM, or ML Use the endpoints to name a line segment. L M H G

10. 8-1 Building Blocks of Geometry Identify the figures in the diagram. Identifying Line Segments and Rays M N O A. three rays B. two line segments MN, NM, MO MN, MO Name the endpoint of a ray first. Use the endpoints in any order to name a segment.

11. 8-1 Building Blocks of Geometry Identify the figures in the diagram. C AB D Check It Out: Example 2 A. three rays B. three line segments BC, CA, BD BA, CA, BD Name the endpoint of a ray first. Use the endpoints in any order to name a segment.

12. 8-1 Building Blocks of Geometry Figures are congruent if they have the same shape and size. Line segments are congruent if they have the same length. You can use tick marks to indicate congruent line segments. In the triangle below, line segments AB and BC are congruent.

13. 8-1 Building Blocks of Geometry Identify the line segments that are congruent in the figure. Identifying Congruent Line Segments AB CD AC BD BF DF EC AE One tick mark Two tick marks Three tick marks The symbol means “ is congruent to.” Reading Math

14. 8-1 Building Blocks of Geometry Example 3 Identify the line segments that are congruent in the figure. AB AC BC DE BD CE One tick mark Two tick marks Three tick marks A B C D E