# Geometry warm up .

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3.1 Symmetry in Polygons. What is symmetry?There are two sorts we\'re concerned with:Rotational and ReflectiveIf a figure has ROTATIONAL symmetry, then you can turn it around a middle and it will coordinate itself (don\'t consider 0
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Slide 1

﻿B E F 30 ° 45° 60 ° 45° A D C Name a beam that cuts up AC or Name the opposite bisector of AC or Name the bisector of <CDB or BD DB BD DF BD DF Geometry warm up D is the midpoint of AC When you complete this, please make another scratch pad

Slide 2

3.1 Symmetry in Polygons What is symmetry? There are two sorts we\'re worried with: Rotational and Reflective If a figure has ROTATIONAL symmetry, then you can pivot it about a middle and it will coordinate itself (don\'t consider 0 ° or 360 °) If a figure has REFLECTIONAL symmetry, it will reflect over a hub. What are polygons? A plane figure framed by at least 3 sections Has straight Sides converge at vertices Only 2 sides cross at any vertex It is a shut figure

Slide 3

Polygons are named by the quantity of sides they have: Names of polygons

Slide 4

Vocabulary Equiangular – All edges are compatible Equilateral – All sides are consistent Regular (polygon) – All edges have a similar measure AND all sides are harmonious Reflectional Symmetry – A figure can be sliced down the middle and reflected over a hub of symmetry. Rotational Symmetry – A figure has rotational symmetry iff it has no less than one rotational picture (not 0 ° or 360 ° ) that concurs with the first picture.

Slide 5

focus Central edge EQUILATERAL triangle has 3 harmonious sides ISOCELES triangle has no less than 2 consistent sides SCALENE triangle has 0 compatible sides Center – in a normal polygon, this is the point equidistant from all vertices Central Angle – An edge whose vertex is the focal point of the polygon somewhat more vocab C

Slide 6

Activities 3.1 Activities 1-2 (give out) Turn it in with your homework

Slide 7

What you ought to have found out about Reflectional symmetry in general polygons When the quantity of sides is even , the hub of symmetry experiences 2 vertices When the quantity of sides is odd , the pivot of symmetry experiences one vertex and is an opposite bisector on the inverse side

Slide 8

What you ought to have found out about rotational symmetry To discover the measure of the focal edge, theta, θ , of a customary polygon, separate 360 ° by the quantity of sides. 360/n = theta To discover the measure of theta in different shapes, ask: "when I turn the shape, how frequently does it arrive on top of the first?" Something with 180° symmetry would have 2-overlay rotational symmetry Something with 90 degree rotational symmetry would be 4-crease

Slide 9

Homework Practice 3.1 A, B & C worksheets

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