Quadrilaterals Sec 6.1

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QuadrilateralsSec 6.1

• GOALS
• To identify, name, describe quadrilaterals
• To find missing measures in quadrilaterals

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Polygons
Polygon a figure that has three or more sides
vertex
side
Specifically

• a plane figure
• a closed figure
• three or more noncolllinear sides
• each side intersects exactly two other sides at
  the vertices

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Polygon or not?

• Identify whether the following figures are
  polygons.

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Naming Polygons

• Polygons are named by the number of sides they
  have.
• Number of sides Name
• 3 triangle
• 4 quadrilateral
• 5 pentagon
• 6 hexagon
• 7 heptagon
• 8 octagon
• 9 nonagon
• 10 decagon
• n n-gon

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Convex and Concave Polygons

• Convex Polygon a polygon where no line that
  contains a side of the polygon contains a point
  in the interior of the polygon.

Point in the interior!
Convex Polygon
Concave Polygon
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Example
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• Name of Polygon
• Convex or Concave?

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Regular Polygon

• Regular Polygon a polygon that is both
  equilateral and equiangular.
• Are the following polygons regular?

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Diagonal of a Polygon

• A segment that joins two nonconsecutive vertices.
• Polygon ABCDE

Diagonals BE and BD
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Angle Measures in Quadrilaterals

• The sum of the measures of the interior angles of
  a quadrilateral is 360 degrees. Theorem 6.1

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Example

• Find the value of y in quadrilateral WXYZ.

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Example

• Find the value of x in quadrilateral WXYZ. Then
  find the measure of angle X and Y.

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Example

• Solve for x and y. Then find the angle measures.

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Homework

• Page 325- See assignment guide