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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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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

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

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

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.

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

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

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

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

Homework Practice 3.1 A, B & C worksheets