Do Now  The measure of angle JKL is 120 degrees. Its supplement is 2x+10. What is the value of x?  Angle A and Angle B are complementary angles. The measure of Angle B is 70 degrees. What is the measure of the supplement of Angle A?

CLASSIFYING POLYGONS

Objective  TLWBAT identify, describe, and classify polygons by using their angles and sides to correctly sort at least 16 out of 20 polygons.  NJCCCS A.1  Common Core 7.G.A.3

Triangles and rectangles are examples of polygons. A polygon is a closed plane figure formed by three or more line segments. Each line segment forms a side of the polygon, and meets, but does not cross, another line segment at a common point. This common point is a vertex of a polygon. The polygon at left has six sides and six vertices. Vertices is plural for vertex. Remember! Side Vertex

Determine whether each figure is a polygon. If it is not, explain why not. Additional Example 1: Identifying Polygons A. B. The figure is a polygon. It is a closed figure with 4 line segments. The figure is not a polygon. It is not a closed figure.

Determine whether each figure is a polygon. If it is not, explain why not. Additional Example 1: Identifying Polygons C. D. The figure is not a polygon. The figure is not formed by line segments. The figure is not a polygon. There are line segments in the figure that intersect.

Determine whether each figure is a polygon. If it is not, explain why not. Check It Out: Example 1 A. B. The figure is a polygon. It is a closed figure with 5 line segments. The figure is not a polygon. It is not a closed figure.

Determine whether each figure is a polygon. If it is not, explain why not. Check It Out: Example 1 C. D. The figure is not a polygon. The figure is not formed by line segments. The figure is not a polygon. There are line segments in the figure that intersect.

Polygons are classified by the number of sides and angles they have. Triangle 3 sides 3 angles Quadrilateral 4 sides 4 angles Pentagon 5 sides 5 angles Hexagon 6 sides 6 angles Heptagon 7 sides 7 angles Octagon 8 sides 8 angles Nonagon 9 sides 9 angles Decagon 10 sides 10 angles

Name each polygon. Additional Example 2: Classifying Polygons A. Octagon B. Quadrilateral

Check It Out: Example 2 Name each polygon. A. B. Quadrilateral Pentagon

A regular polygon is a polygon in which all sides are congruent and all angles are congruent.

Additional Example 3: Identifying and Classifying Regular Polygons Name each polygon and tell whether it is a regular polygon. If it is not, explain why not. The figure is a regular quadrilateral. A regular quadrilateral is also called a square. The figure is a quadrilateral. It is an irregular polygon because all of the sides are not congruent. A. B.

Check It Out: Example 3 The figure is a triangle. It is an irregular polygon because all sides and angles are not congruent. The figure has congruent angles and congruent sides. The figure is a regular triangle. Name each polygon and tell whether it is a regular polygon. If it is not, explain why not. A. B.

Classifying Triangles by Sides  Scalene triangle – no congruent (equal) sides  Isosceles triangle – two congruent (equal) sides  Equilateral triangle – all three sides are congruent (equal)

Classifying Triangles by Angles  Right triangle – has exactly one right angle  Acute triangle – all the angles are acute. There are no right angles and no obtuse angles.  Obtuse triangle – has exactly one obtuse angle

Classifying Quadrilaterals  Any shape with four sides and four angles is a quadrilateral.

Parallelogram  Opposite sides are parallel and congruent (equal). Opposite angles are congruent.

Rectangle  A type of parallelogram with four right angles.

Rhombus  A type of parallelogram with four congruent (equal) sides.

Square  A type of parallelogram with four congruent (equal) sides and four right angles.

Trapezoid  Only one pair of opposite sides is parallel. This is NOT considered a parallelogram!

Pentagon  A polygon with 5 sides and 5 angles  Which is the regular pentagon?

Hexagon  A polygon with 6 sides and 6 angles  Which is the regular hexagon?

Heptagon  A polygon with 7 sides and 7 angles  Which is the regular heptagon?

Octagon  A polygon with 8 sides and 8 angles  Which is the regular octagon?

Nonagon  A polygon with 9 sides and 9 angles  Which is the regular nonagon?

Decagon  A polygon with 9 sides and 9 angles  Which is the regular Decagon?

A circle is the set of all points in a plane that are the same distance from a given point, called the center of a circle. A circle is named by its center. For example, if point A is the center of a circle, then the name of the circle is circle A. There are special names for the different parts of a circle. A

Radius Line segment whose endpoints are the center of a circle and any point on the circle Diameter Line segment that passes through the center of a circle, and whose endpoints lie on the circle A

Name the parts of circle M. Additional Example 1: Identifying Parts of a Circle O N Q R M A. radii: B. diameters: MN, MR, MQ, MO NR, QO Radii is the plural form of radius. Reading Math

Name the parts of circle M. Check It Out: Example 1 A. radii: B. diameters: GB, GA, GF, GD BF, AD A B D F G

Exit Ticket  Find the value of x.