# Classify ing TwoDimensional Figur es Classifying 2-Dimensional Figures Classify ing TwoDimensional Figur es Classifying 2-Dimensional Figures Lets look at some vocabulary terms before we start classifying figures. Two-dimensional having a width and a height but flat like a piece of paper. Polygon Two-dimensions Polygon a two-dimensional shape made up of straight lines that are closed. Three-dimensions

One-dimension Classifying 2-Dimensional Figuresare either regular or irregular. Polygons This is a regular pentagon because ALL of its sides and angles are congruent. Congruent having the same measure Hash marks indicate sides with the same length. Angle arcs indicate angles of the same measure. This is an irregular pentagon because some of its sides and angles are not congruent. Classifying 2-Dimensional Figures Here is a list of the most basic polygons: 3-sided 4-sided

5-sided 6-sided Triangle 7-sided Septagon Quadrilateral 8-sided Octagon 9-sided Nonagon 10-sided

Decagon Pentagon Hexagon i y f i s s a l C ng a u Q ls

a l i r d r te Properties of Quadrilaterals A main group of polygons are the quadrilaterals. All quadrilaterals have: 4 sides 4 angles (that add up to 360) Classifying Quadrilaterals

We classify quadrilaterals based on whether or not they have certain properties: How many sets of parallel sides it has Parallel Line -Two lines on the same plane that will never cross. They are always the same distance apart. Classifying Quadrilaterals We classify quadrilaterals based on whether or not they have certain properties: The number of congruent sides it has Congruent having the same measure, indicated by hash lines These sides are congruent

These sides are congruent Classifying Quadrilaterals We classify quadrilaterals based on whether or not they have certain properties: If it contain right angles Right angles = 90 degrees, indicated by a square in the corner Classifying Quadrilaterals Lets classify quadrilaterals from those with the fewest properties to those with the most properties. Quadrilateral with no

parallel or congruent sides Quadrilateral with one pair of parallel sides Trapezoid Basic Quadrilateral Classifying Quadrilaterals Two pairs A parallelogram of parallel sides Opposite sides congruent Four 90 angles Parallelogram

Rectangle By definition, rectangles are considered parallelograms. Why cant parallelograms be classified as rectangles? Parallelograms do not have 4 90 degree angles. Classifying Quadrilaterals A parallelogram A parallelogram 4 congruent sides Rhombus A rectangle A rhombus

Square Why can we classify a square as a rectangle and a rhombus? A square is a parallelogram with 4 right angles (rectangle) A square is a parallelogram with 4 congruent sides (rhombus) triangle pentagon rectangle parallelogram right triangle octagon trapezoid square rhombus

5. tria ng World Cup 2014 1. YIELD trapezoid tria ngl WORD BANK Higher

Coff Grounds ee 3. parallelogram F FA Future Farmers of America le ITALIA 6. e Classifying 2-Dimensional Figures

Name each of the following polygons. 2. 4. Work Zone trapezoid Trail 3 pentagon Classifying 2-Dimensional Figures Answer the following questions. 1. What do the hash marks indicate on the sides of polygons? Hash marks indicate that those side lengths are congruent. 2. Whats the difference between a regular and irregular polygon?

A regular polygon has sides and angles that are all congruent. An irregular polygon does not. 3. By definition, we can classify all rectangles as parallelograms, but why cant we classify parallelograms as rectangles? A rectangle has two pairs of parallel sides and two pairs of congruent sides as defined by a parallelogram. However, a rectangle has four 90 right angles which is not included in the definition of a parallelogram. 4. Whats the difference between an obtuse angle and an acute angle? Classifying 2D Figures Match each term with one of the figures. A B G 3. Pentagon _____ F 4. Trapezoid ________ 1. Triangle _____ 2. Rhombus _____ E 5. Octagon _____

D C 7. Quadrilateral _____ 6. Parallelogram _____ E A F G C D 120 B i y

f i s s a l C ng a i r T e l g n Properties of Triangles

All triangles have: 3 sides 3 angles (that add up to 180) There are just a few basic ways that we classify or name triangles! Classifying Triangles We classify or name triangles by their angles. All angles < 90 One 90 angle Acute Triangle Right Triangle

Obtuse Triangle One angle > 90 Classifying Triangles We also classify triangles by their side lengths and angle measures. 3 congruent sides All angles congruent Equilateral Triangle 2 congruent sides 2 congruent angles Isosceles Triangle

No congruent sides No congruent angles Scalene Triangle Name that Triangle! Classify each triangle by ALL names that apply. 2. ____________________ Acute 1. ____________________ Isosceles 3.

____________________ Right ____________________ Isosceles 140 Obtuse ____________________ Scalene ____________________