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# Welcome To Geometry

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### Welcome To Geometry

1. 1. Welcome to Geometry!!! One thing that is different about geometry is the amount of vocabulary you need to "master". It is a lot, but it's not impossible.
2. 2. Point: An exact location in space. Usually represented with a "." in math problems and examples. In our room examples: the dot on the i in scottish on the clock. the corners (vertex) of pennant, book, piece of paper.
3. 3. Line: A straight path of points that go on and on in both directions. Represented with In math problems and examples Sort of examples of lines (line segments) in our room: Where the wall meets the ceiling The edge of a desk grids on the ceiling top of the chalkboard the edge of most posters or pieces of paper
4. 4. Plane: A surface with only 2 dimensions. Examples of planes in our room. coverings of ceiling lights Floor A whiteboard Smart board screen ceiling
5. 5. Types of Lines: Parallel : Lines that never cross Examples: top and bottom edge of smart board, chalkboards, and most whiteboards. Intersecting: Lines that cross at one point: Examples: edges of the pennants, the edges of the stars on the American Flag, top edge of north and south walls Perpendicular: Lines that intersect at right angles. Examples:
6. 6. Angle: A figure formed by two line segments or rays that have same endpoint. Or at the intersection of lines. angle
7. 7. Acute angle: an angle less than a right angle. Think small and 'cute' Right Angle: An angles that measures 90 degrees (right angle) Obtuse Angle: An angle greater than a right angle. Think Ob, Obese (fat)
8. 8. Polygon: A closed figure made of line segments: Examples of Polygons: Not Polygons: Closed, but not line segments Line Segments, but not closed
9. 9. Triangles: A polygon with 3 sides We name triangles by angles and side lengths. For example the red triangle above is a right isosceles triangle Huh?
10. 10. Naming triangles by angle types 1) Right Triangles have a right or 90 degree angle in them. Angle BCA is right ... the little square is a 'math note' that means right angle. 2) Acute Triangles have all acute or less than 90 degree angles in them. See how all the angles are acute. 3) Obtuse Triangles have 1 obtuse or larger than 90 degree angle in them. A Angle ABC is an obtuse angle B C
11. 11. Naming Triangles by side lengths Scalene Triangles have no congruent (same size) sides (and not congruent angles) A B None of the sides are congruent C Isosceles Triangles have 2 congruent sides (and 2 congruent angles) Side GH and Side GI are same length, the little 'hash marks' are a 'math note' saying that. Equilateral Triangles have 3 congruent sides (and 3 congruent angles) The little 'hash marks' show all sides are the same length.
12. 12. Putting it all together. Look at the triangle below Start with angle type: Right ... Then look at side lenghts: Scalene So ABC is a right scalene triangle
13. 13. Let's try some more: 1)Acute Isosceles 1) (3 acute angles/2 congruent sides) 2) Equilateral 2) (3 congruent sides) 3) Obtuse Scalene 3) (1 obtuse angle/0 congruent sides)
14. 14. Quadrilaterals: Four sided polygons. Like triangles, special quadrilaterals can be named or classified by sides and angles. Look at the next page, to see how this is done.
15. 15. Special Quadrilateral Types related oddball See how the definitions are so similar in these 4. Trapezoid: Parallelogram: Both sets of opposites are parallel. Opposite sides are congruent. Opposite angles are congruent. Only one set of opposite sides Rectangle: Both sets of opposites are parallel. Opposite is parallel. sides are congruent. All angles are right angles. Rhombus: Both sets of opposites are parallel. Opposite sides are congruent. All sides are congruent Square: Both sets of opposites are parallel. All angles are congruent. All angles are right angles.
16. 16. Classifying Geometric Shapes Polygons Not Polygons
17. 17. Classifying Geometric Shapes Quadrilaterals Has Acute Angles
18. 18. Classifying Geometric Shapes All Congruent Sides At least 2 Congruent Angles