Understanding Undefined and Defined Terms in Geometry
This guide explores key concepts in geometry, focusing on undefined and defined terms such as points, lines, and planes. It explains how these terms are used, providing examples of collinear and coplanar points. Additionally, it includes exercises for naming segments, rays, and identifying intersections in diagrams. Tools for visualizing geometric relationships are presented, along with practice problems to reinforce understanding of how various geometric elements interact. Perfect for students looking to grasp the fundamentals of geometry.
Understanding Undefined and Defined Terms in Geometry
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Presentation Transcript
Undefined Terms Words that do not have formal definitions but there is an agreement about what they mean.
Defined Terms Terms that can be described using known terms like Point or Line
a. Give two other names for PQand for plane R. b.Name three points that are collinear. Name four points that are coplanar. • Other names for PQare QPand line n. Other names for plane Rare plane SVT and plane PTV. EXAMPLE 1 Name points, lines, and planes SOLUTION
EXAMPLE 1 Name points, lines, and planes b. Points S, P, and Tlie on the same line, so they are collinear. Points S, P, T,and Vlie in the same plane, so they are coplanar.
1. Use the diagram in Example 1. Give two other names for ST. Name a point that is not coplanar with points Q, S, and T. ANSWER TS, PT; point V for Example 1 GUIDED PRACTICE
a. Give another name for GH . a. Another name for GHis HG . b. The rays with endpoint Jare JE, JG, JF, and JH . The pairs of opposite rays with endpoint Jare JEand JF, and JGand JH. EXAMPLE 2 Name segments, rays, and opposite rays b. Name all rays with endpoint J . Which of these rays are opposite rays? SOLUTION
2. Give another name for EF ANSWER FE 3. Are HJand JH the same ray ? Are HJand HGthe same ray? Explain. ANSWER No; the rays have different endpoints.Yes; points J and G lie on the same side of H. for Example 2 GUIDED PRACTICE
c. a. b. EXAMPLE 3 Sketch intersections of lines and planes a. Sketch a plane and a line that is in the plane. b.Sketch a plane and a line that does not intersect the plane. c. Sketch a plane and a line that intersects the plane at a point. SOLUTION
STEP 1 Draw: a vertical plane. Shade the plane. STEP 2 Draw: a second plane that is horizontal. Shade this plane a different color. Use dashed lines to show where one plane is hidden. STEP 3 Draw: the line of intersection. EXAMPLE 4 Sketch intersections of planes Sketch two planes that intersect in a line. SOLUTION
ANSWER Use the diagram at the right. 5. Name the intersection of PQand line k. ANSWER Point M for Examples 3 and 4 GUIDED PRACTICE • Sketch two different lines that intersect a plane at the same point.
ANSWER Linek Use the diagram at the right. ANSWER Linek for Examples 3 and 4 GUIDED PRACTICE 6. Name the intersection of plane A and plane B. 7. Name the intersection of line kand plane A.
