Polygon?
A shape with 5 sides is called a
Pentagon
Formula for the sum of interior angles of an n-sided polygon?
(n−2)×180°
Formula for circumference?
C=2πr or πd
The distance from the center of a circle to a point on the circle.
Radius
What’s the relationship between the radius and diameter?
Diameter = 2 × radius
A polygon with all equal sides and angles is called
Regular Polygon
What is the sum of interior angles of a hexagon?
(6−2)×180=720°
Formula for area?
A = πr²
A line that passes through the center and touches both sides of a circle
Diameter
Find the number of sides in a polygon with an interior angle sum of 1080°.
(n−2)×180=1080→n=8
True or False: A star is a concave polygon.
True
Find one interior angle of a regular octagon.
(8−2)×180÷8=135°
Find the circumference of a circle with radius 5 cm.
2π(5) = 10π ≈ 31.4
What is a polygon?
A closed 2D shape with straight sides
Find the area of a circle with radius 12 cm.
π(122)=144π ≈ 452.4 cm²
What’s the difference between a convex and concave polygon?
Convex = all vertices point outward
Concave = at least one points inward.
Each exterior angle of a regular polygon is 45°
360 ÷ 45 = 8
Find the area of a circle with diameter 10 cm.
r=5→A=25π≈78.5 cm²
Classify the six types of polygons we discussed in class
Triangles (3 sides)
Quadrilaterals (4 sides)
Pentagons (5 sides)
Hexagons (6 sides)
Heptagons (7 sides)
Octagons (8 sides)
Find one exterior angle of a regular nonagon.
360÷9=40°
Name a polygon that has 12 sides
Dodecagon
A regular polygon has interior angles of 150°. How many sides does it have?
(n−2)×180÷n=150→n=12
A circle has a circumference of 62.8 cm. Find the radius.
62.8=2πr→r=10 cm
A polygon with no equal length and has different angle measurements is called
Irregular Polygons
What is Ms. Borrero's favorite polygon?
Heptagon