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Chapter/Lesson: Chapter 9 Lessons 7, 8, 12 Pages: 404/408/418
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Objective/Title: Geometric Shape Properties/Lines of Symmetry
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Important Terms
Quick Solve
Congruent: same/equal size (side length
or angle measure)
Parallel: lines that are the same
distance apart and do not intersect
Perpendicular: lines that intersect
forming right angles
Symmetry: a line that is drawn which
separates the figure into 2 equal parts;
both sides look the same when folded
Practice Questions
Geometric Shape Properties
Read each statement below and decide if it is: always true, sometimes true, or never true.
1. Parallelograms are squares sometimes
2. All squares are rectangles always
Draw the lines
of symmetry
3. Rhombuses are squares sometimes
Square: 4
4. All rectangles are squares never
5. All squares are parallelograms always
6. All trapezoids are quadrilaterals always
Pentagon: 5
7. Triangles can have 2 obtuse angles never
8. Trapezoids are parallelograms never
Isosceles: 1
Rectangle: 2
9. An equilateral triangle has all sides equal always
10. A scalene triangle can have 2 sides equal never
Circle
:
Many
11. A scalene triangle has 0/No sides equal.
12. A right triangle has one 90 degree angle.
13. A trapezoid only has one pair of parallel lines.
14. List 3 specific types of parallelograms rhombus, square, rectangle
15. A pentagon has 5 sides, a hexagon has 6 sides, and an octagon has 8 sides
Rectangle
16. Draw an example of a parallelogram that is NOT a rhombus.
Square
Parallelogram
Notes and Examples
Acute- less than 90°
Types of Angles
Obtuse- more than 90 ° Right- exactly 90°
Classification of Triangle by Sides
Isosceles:
1. Scalene:
 2 sides are congruent
 No sides are congruent
Equilateral:
 All sides are congruent
 All angles are congruent
60°
 3 lines of symmetry
1. Right:
 One 90° angle
Straight- exactly 180°
 2 angles are congruent
 No angles are congruent
 1 line of symmetry
 No lines of symmetry
Classification of Triangle by Angles (only classify by angle if asked)
2. Acute:
Obtuse:
 Three acute angles
 One obtuse angle
 You can never have more than
one obtuse angle in a triangle
Quadrilaterals
Parallelogram:
 Opposite sides are parallel
Rectangle:
 Four right angles
 Opposite sides are congruent
 Parallelogram
Square:
 All four sides are congruent
 Four right angles
 Rectangle
 Opposite angles are congruent
Rhombus:
 Opposite angles are congruent
 All sides are congruent
 Parallelogram
 May be a square
 Parallelogram
Trapezoid:
 One pair of parallel lines
Kite:
 2 pairs of congruent sides
 No parallel lines
 1 line of symmetry
*Isosceles Trapezoid also has one
pair of congruent sides
Polygons (Shapes with 3 or more straight sides that meet)
Regular polygons: all sides and angles are congruent; these are the shapes we are used to seeing (shaded figure)
Triangle
3 sides
Quadrilateral
4 sides
Pentagon
5 sides
Hexagon
6 sides
Heptagon
7 sides
Octagon
8 sides
Nonagon
9 sides
Decagon
10 sides
Undecagon
11 sides
Dodecagon
12 sides
A line of symmetry evenly divides the shape in half
Yes this is a line of symmetry
No this is not a line of symmetry
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