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## POINTS, LINES, AND PLANES

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**UNDEFINED TERMS**• Terms defined only by examples and descriptions • Point: a location • Line: a set of points that goes on infinitely in both directions and has no thickness or width • Plane: a flat surface made up of points**OTHER VOCABULARY**• Collinear: on the same line • Coplanar: in the same plane • Space: a boundless three-dimensional set of all points • Locus: a set of points that satisfies a particular condition.**Name a line containing point A.**• Name a plane containing point C.**How many planes are shaded in the figure?**• Name three points that are collinear • Are points A, C, D, and J Coplanar? Explain.**PRACTICE**• Pg. 9 #13-17, 21-35**Precision: a measurement precise to within .5 units of**measure Definitions • Line Segment: The part of a line between two end points • Between: point M is between points P and Q only if PM + MQ = PQ • Congruent: exactly the same size and shape**Find the precision for each measurement:**Examples A. 5 millimeters Since the measurement is accurate to the nearest millimeter, the measurement must be accurate to the nearest .5 millimeter. So the precision is from 4.5 to 5.5 millimeters. B. 8 1/2 inches Since the measurement is accurate to the nearest 1/2 inch, the measurement must be accurate to the nearest 1/4 inch. So the precision is from 8 1/4 inches to 8 3/4 inches.**Practice**• Pg. 17 #12-27, 34-39**Definitions**• Midpoint-the point halfway between two points • Bisect-to cut in half**Midpoint Formula**Average the x's and average the y's**Examples**• Find the midpoint between (2,6) and (0,0) • Find the midpoint between (-5,-3) and (7,9)**Examples**• Find the distance between the points (2,5) and (5,9)**Examples**• Find the distance between the points (0,5) and (5,-7)**Practice**• Pg. 25 #13-22**DEFINITIONS**• Ray: a part of a line from one endpoint extending infinitely in one direction. • Angle: two rays that share an endpoint. • Vertex: the common endpoint of the two rays in an angle.**DEFINITIONS**• Interior: inside of the angle. • Exterior: outside of the angle.**ANGLE CLASSIFICATIONS**• Right angle: 1/4 of a circle; 90 degrees • Obtuse : greater than 90 degrees • Acute : less than 90 degrees**EXAMPLES**• Name the vertex of angle 2 • C • Name the sides of angle 4 • BA and BC • What is another name for angle BDC • Angle CDB or Angle 1**EXAMPLES**Angle RQT=47**EXAMPLES**Angle TQS=22**PRACTICE**• Pg. 34 #12-23**DEFINITIONS**• Adjacent Angles: Angles that share a side and do not overlap: • Vertical Angles: two nonadjacent angles formed by two intersecting lines:**DEFINITIONS**• Linear pair: a pair of adjacent angles that form a straight line: • Complementary Angles: a pair of angles whose sum is 90 degrees • Supplementary Angles: a pair of angles whose sum is 180 degrees • Perpendicular: lines that form right angles.**EXAMPLES**Name a pair of adjacent angles One example: VZX AND XZW Name a pair of vertical angles VZX and YZW or VZY and XZW Name a linear pair Two examples: VZX and YZW or VZY and WZW**PRACTICE**• Pg 42 #11-35**DEFINITIONS**• Not Polygons: • Polygons: • Polygon: a closed figure where all sides are segments • Regular Polygon: a polygon where all sides and all angles are congruent**DEFINITIONS**• Concave and Convex: • Concave: • Convex: • Trick to remember: Concave figures have "hiding spots," just like a cave. • Perimeter: the sum of the lengths of the sides of a polygon.**EXAMPLE**WORK THROUGH ON BOARD 16 UNITS**PRACTICE**• Pg. 48 #12-31