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TRANSCRIPT
1.4 Perimeter and Area in the Coordinate Plane
• Classify polygons • Find perimeters and
areas of polygons in the coordinate plane
VOCABULARY
WHAT YOU WILL LEARN
• polygon • side • vertex • n-gon • convex • concave
Vocabulary: Polygon, Sides, and Vertex
• In geometry, a figure that lies in a plane is called a plane figure. A polygon is a closed plane figure formed by three or more line segments called sides. Each side intersects exactly two sides, one at each vertex, so that no two sides with a common vertex are collinear.
• You can name a polygon by listing the vertices in consecutive order.
Naming Polygons
• The number of sides determines the name of a polygon.
Number of sides Type of polygon
3 Triangle4 Quadrilateral5 Pentagon6 Hexagon7 Heptagon8 Octagon9 Nonagon10 Decagon12 Dodecagonn n-gon
• You can also name a polygon using the term n-gon, where n is the number of sides. For example, a 52-gon is a polygon with 52 sides.
Vocabulary: Convex and Concave
• A polygon is convex when no line that contains a side of the polygon contains a point in the interior of the polygon.
• A polygon is concave when there is a line that contains a side of the polygon and contains a point in the interior of the polygon.
Example 1
• Classify each polygon by the number of sides. Also, tell whether it is convex or concave.
Perimeter and Area in the Coordinate Plane
• Whenever you are working with the coordinate plane, remember that you can use the Distance Formula to help with perimeter and area.
• Here are some helpful formulas that may look familiar for triangles, squares, and rectangles:
Example 4
• You are making a bumper sticker for a graphic design project. The four vertices of the bumper stick fall on the coordinate plane as shown. Each unit in the coordinate plane represents 2 inch. Find the area of the bumper sticker.