Download Is it a Polygon?

CH. 7 GEOMETRY
POLYGONS
A polygon is a 2-dimensional shape with straight sides.
Is it a Polygon?
Polygons are 2-dimensional shapes. They are made of straight lines, and the shape is "closed" (all the lines
connect up).
Not a Polygon
(has a curve)
Polygon
(straight sides)
Not a Polygon
(open, not closed)
QUADRILATERALS (4-sided polygons): Angles of a quadrilateral add up to 360 degrees.
Parallelogram
Rhombus
Rectangle
(opposite sides parallel, (all sides same size)
and the same size,
and opposite angles are the same)
Square
(each angle 90°)
Trapezoid (only 2 sides are parallel)
(each angle 90°
and all sides same size)
Triangles
Scalene Triangle
(no sides the same)
Isosceles Triangle
(2 sides the same)
Equilateral Triangle
(3 sides the same)
Angles of a triangle add up to 180 degrees.
Perimeter – distance around the edges of an object
Perimeter of a square = 4s, where s = length of one side
Perimeter of a rectangle = 2W + 2L, where W = width and L = length
Perimeter of a triangle = side 1 + side 2 + side 3
Area – amount of surface covered by an object.
Area of a square = s2
Area of a rectangle = L• W
Area of a triangle = ½ •b•h, where b = length of base and h = height
Area of a parallelogram = b•h b = length of base and h = height
Right Triangle
(one angle is 90°)
CIRCLES:
A circle is the set of all points that are a fixed distance from the center.
The fixed distance is called the radius, often abbreviated by the variable, r.
The diameter starts at one side of the circle, goes through the center and ends on the other side.
So the Diameter is twice the Radius:
Circle Sector and Segment
Diameter = 2 × Radius = 2r
Radius = Diameter / 2
Slices
There are two main "slices" of
a circle.
The "pizza" slice is called a
Sector.
Center
And the slice made by a chord
is called a Segment.
Common Sectors
The Quadrant and Semicircle are two special types of Sector:
Given this property, you can make a formula for
the circumference by multiplying both sides of this equation
by the diameter.
Circumference
  ( Diameter)
Diameter
Circumference   (Diameter)
Circumference   (2r )  2r
(Diameter)
Quarter of a circle
is called a
Quadrant.
Half a circle is
called a
Semicircle.
Area of a Circle:
If you make a parallelogram out of a circle by piecing together the
slices of pie, you will use half the circumference for one base and
half the circumference for the other base (so base = ½(2πr)=πr).
The height of the parallelogram will be the radius, r.
Now we now the area of a parallelogram is base X height.
So the area of a circle is (πr)(r).
Area of a Circle = πr2