topic 9 vocab
TRANSCRIPT
February 08, 2013
Topic 9: Lines, Shapes and Angles (2D Geometry)Important Terms:
Point: A definite location in space.Line: A series of points that goes forever in both directions.Plane: an infinitely large 2 dimensional (flat) surface.
Points and lines "rest" on a plane. A solid shape, like a cube has multiple planes. Each face of the cube is its own plane.
February 08, 2013
Topic 9: Lines, Shapes and Angles (2D Geometry)Important Terms: Digging Deeper with Lines
Line Segment: Part of a line, has endpoints
Ray: Part of a line that has one endpoint, other end continues forever in one direction.
Angle: 2 rays or line segments that meet at a common point.
February 08, 2013
Topic 9: Lines, Shapes and Angles (2D Geometry)Important Terms: Digging Deeper with Lines
Parallel Lines: 2 lines that never intersect
Intersecting Lines: 2 lines that cross paths
Perpendicular lines: 2 lines that intersect at a right angle (90º)
Note: The terms parallel, intersecting and perpendicular can be used with rays and line segments.
Square Symbol is frequently used to show a right angle
February 08, 2013
Topic 9: Lines, Shapes and Angles (2D Geometry)Important Terms: Digging Deeper with Angles
Acute Angle: An angle that measures less than 90º(0º < Acute Angle < 90º)
Right Angle: An angle that measures exactly 90º(Think corner of a square)
Obtuse Angle: An angle that is greater than 90º(90º < Obtuse Angle < 180º)
acute is like "cute"
obtuse is like obese
February 08, 2013
Topic 9: Lines, Shapes and Angles (2D Geometry)Important Terms: Creating Shapes with Angles and Line SegmentsPolygon: A closed figure (shape) that only has line segments for sides.
Triangle: A 3-sided polygon
Quadrilateral: a 4-sided polygon
Pentagon: a 5-sided polygon
Hexagon: a 6-sided polygon
Octagon: an 8-sided polygon
Polygons Not Polygons
February 08, 2013
Topic 9: Lines, Shapes and Angles (2D Geometry)Focus on Triangles:Triangles are named by their angle types and side lengths
Angle Naming Side Naming
February 08, 2013
The best possible names for triangles use both angle and side names. Exception is equliateral
acute scalene: all acute angles, no sides congruentacute isosceles: all acute angles, 2 sides congruentequilateral: all acute angles, all sides congruent
right scalene: one right angle, no sides congruentright isosceles: one right angle, 2 sides congruent
obtuse scalene: one obtuse angle, no sides congruentobtuse isosceles: one obtuse angle, 2 sides congruent
February 08, 2013
Topic 9: Lines, Shapes and Angles (2D Geometry)Focus on Triangles:Triangles are named by their angle types and side lengths
The best way to name a triangle is with both the angle name and side name:
Acute Isosceles Obtuse Scalene Right Isoceles all acute angles 1 obtuse angle 1 right angle 2 equal sides 0 equal sides 2 equal sides
Special Case!
An Equilateral Triangle is a triangle with 3 equal sides. You don't need to call it an "Acute Equliateral", it's just an Equilateral.
February 08, 2013
Topic 9: Lines, Shapes and Angles (2D Geometry)Focus on QuadrilateralsQuadrilaterals are 4-sided polygonsQuadrilaterals are classified or named by how their sides relate to each other. We need to use the most specific name.
"Congruent" = same size or same length
February 08, 2013
Topic 9: Lines, Shapes and Angles (2D Geometry)Focus on Quadrilaterals
The sequence below might help to show why when we name a quadrilateral we need to use the most specific name.
yes
yes
yes
yes
YES! .... and the most specific name
February 08, 2013
Best name: parallelogram
Properties: 1, 2
Properties to consider1) 4 sides2) pairs of parallel sides3) congruent sides4) right angles
February 08, 2013
Best name: rectangle
Properties: 1, 2, 4
Properties to consider1) 4 sides2) pairs of parallel sides3) congruent sides4) right angles
February 08, 2013
Best name:squareProperties: 1,2,3, 4
Properties to consider1) 4 sides2) pairs of parallel sides3) congruent sides4) right angles
February 08, 2013
Best name: Rhombus
Properties: 1,2,3
Properties to consider1) 4 sides2) pairs of parallel sides3) congruent sides4) right angles
February 08, 2013
Best name: Quadrilateral
Properties: 1
Properties to consider1) 4 sides2) pairs of parallel sides3) congruent sides4) right angles
February 08, 2013
Best name: right scalene triangle
Properties: Has a right angleNo sides are congruent
Best name: right isosceles triangle
Properties: Has a right angle2 sides are congruent
February 08, 2013
Best name: acute angle
Properties: smaller than 90º
February 08, 2013
Best name: intersecting line segments
Properties:
cross, but not at a right angle