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Exploring Polygons

Exploring Polygons. What are polygons? A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others

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Page 1: Exploring Polygons. What are polygons? A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others

Exploring Polygons

Page 2: Exploring Polygons. What are polygons? A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others

What are polygons?

A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others.

The following are examples of polygons:

Page 3: Exploring Polygons. What are polygons? A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others

The figures below are not polygons. Can you tell why?

Page 4: Exploring Polygons. What are polygons? A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others

Regular Polygons

A regular polygon is a polygon whose sides are all the same length, and whose angles are all the same.

The following are examples of regular polygons:

Would a square be a regular polygon? A rectangle?

Page 5: Exploring Polygons. What are polygons? A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others

The following are not examples of regular polygons:

How do you know?

Page 6: Exploring Polygons. What are polygons? A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others

TrianglesAll three-sided polygons.

There are many special types of triangles.

Page 7: Exploring Polygons. What are polygons? A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others

QuadrilateralA four-sided polygon.

Page 8: Exploring Polygons. What are polygons? A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others

Angles in quadrilaterals…Quadrilaterals have four sides and four angles.

The sum of the measures of the angles is 360°.

Find the value of x in the quadrilateral below

x° + 105° + 80° + 95° = 360°

Add 105°, 80°, and 95°.

x° + 280° = 360°

THINK: What measure

added to 280° equals 360°?

80° + 280° = 360°

x° = 80°

Page 9: Exploring Polygons. What are polygons? A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others

Find the value of x in each quadrilateral.

Page 10: Exploring Polygons. What are polygons? A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others

A rectangle has opposite sides congruent and parallel, and all right

angles.

Are rectangles a kind of quadrilateral?

How do you know?

Page 11: Exploring Polygons. What are polygons? A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others

A square has all sides congruent, opposite sides parallel, and all right

angles.

Are squares a kind of rectangle?

How do you know?

Page 12: Exploring Polygons. What are polygons? A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others

A parallelogram has opposite sides congruent and parallel, and opposite

angles congruent.

Are parallelograms a kind of rectangle? How do you know?

Page 13: Exploring Polygons. What are polygons? A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others

A rhombus has all sides congruent, opposite sides parallel, and opposite

angles congruent.

How are rhombuses and squares similar? How are rhombuses and squares different?

Page 14: Exploring Polygons. What are polygons? A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others

A trapezoid has exactly one pair of opposite sides parallel.

There are special types of trapezoids ….that’s for another day!

Page 15: Exploring Polygons. What are polygons? A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others

Classify each quadrilateral.

Page 16: Exploring Polygons. What are polygons? A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others

PentagonA five-sided polygon

a regular pentagon

an irregular pentagon

Page 17: Exploring Polygons. What are polygons? A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others

HexagonA six-sided polygon.

a regular hexagon

an irregular hexagon

Page 18: Exploring Polygons. What are polygons? A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others

HeptagonA seven-sided polygon

A regular heptagon

an irregular heptagon

Page 19: Exploring Polygons. What are polygons? A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others

OctagonAn eight-sided polygon.

A regular octagon

An irregular octagon

Page 20: Exploring Polygons. What are polygons? A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others

NonagonA nine-sided polygon.

A regular nonagon

An irregular nonagon

Page 21: Exploring Polygons. What are polygons? A polygon is a closed figure made by joining line segments, where each line segment intersects exactly two others

DecagonA ten-sided polygon.

A regular decagon

An irregular decagon