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1.1 Building Blocks of Geometry Identifying lines, rays, and segments VOCABULARY Point – usually labeled with an uppercase letter. Describes a specific location in space. Line – points that extend without end in two opposite directions Read as: “line NO or line ON” N O Symbol: NO or ON Ray – has one endpoint and extends without end in one direction. Always when naming give the endpoint first. B A Read as: “ray AB” Symbol: AB Identifying lines, rays, and segments continued…. Segment – a piece of a line which has two endpoints ● ● B E Read as: “line segment BE or line segment EB” Symbol: BE or EB NOTE: You may have the points at the end of the segment or without. Plane – flat surface that extends indefinitely along its length and width Read as: plane ABC Identifying lines, rays, and segments continued…. Parallel lines – two different lines that will never intersect no matter how far they extend. C D “Line CD is parallel to line YZ.” Y CD | | YZ Z Intersecting lines – two different lines that meet at a point Q T S P “Line TS intersects with line PQ” Let’s Do Some Examples! Identify and name the line, ray, or segment. S M 1. N ray MN or 2. Q ● 3. R line segment NM P ● QP or PQ line RS or SR Now You Try! Identify and name the line, ray, or segment. G ray GF or FG F line H ● K HJ or JH J L ● segment KL or LK Now You Try Continued G H J K L 1. Name 2 rays. HL or GK or JL or JK 2. Name 2 segments that have G as an endpoint. 3. Name a line. GH 4. Name 3 points. GH and GJ Any 3 that includes L or J or K or H or G Now You Try Continued A B C D G F E 1. Name a pair of intersecting lines. 2. Name a pair of parallel lines. 3. Name DB and BA another way. AB and EG or CF and EG AB and CF BD and AB Midpoint Midpoint – The midpoint of a segment is the point on the segment that is the same distance from both endpoints. Bisects – The midpoint bisects the segment, meaning that it divides it into two congruent segments M is the midpoint of AB. 1.2 Angles What is an angle? Angle – An angle is formed by two rays that share a common endpoint Vertex – The common endpoint of the two rays Sides – The two rays Point B is the vertex of angle ABC. The angle may also be referred to as angle CBA, angle B, , or Angle measures Angle measures – can be anywhere between 0 and 180 degrees. “The measure of angle A is 45 degrees” Using a protractor 1) Place hole in center of protractor on vertex 2) Align first ray along line on bottom of protractor 3) Use other ray to find angle measure