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 READY REFERENCE 
Surface Measurement
Perimeter and Area  1
Line:
We saw line as one dimension.
Suppose we have line segment AB.
A __________________ B 
If we add another line segment eg. CD
C _________________ D 
Now we have two line segments.
These two lines can be arranged in different ways.
These lines can be parallel to each other.
A _______________ B 
C _______________ D 
These can be at an angle to each other. or
They can be perpendicular to each other.
If you add another line third line, fourth line, etc, they make different shapes or different Geometric figures.
For example:
Triangle  Square  Rectangle  Parallelogram  Trapezoid 
These are all Polygons.
Polygons have many sides. Polygons are named for the number of sides they have.
Pentagon  Hexagon  Quadrilateral  Heptagon  Octagon 
Polygons can be Regular or Irregular.
If all the sides are of the same length and all the angles have the same measure, the polygon is called the regular polygon.
Just as by adding more lines we made above different figures, by bending or curving the line or by adding curved line segments we can make different circular figures.
For example:


Circle  Ellipse 
Table of Surface Measure
Traditional System
144 square inches = 1 sq. ft.
9 square feet = 1 sq. yard
30 1/4 sq. yds. = 1 sq. rod
160 sq. rods. = 1 acre
640 acres = 1 sq. mile
1 acre = 208.71 ft. x 208.71 ft.
Table of Surface Measure
Metric System
meter x 10 = decameter
meter x 100 = hectometer
meter x 1000 = kilometer
Conversion between metric and customary systems
CUSTOMARY  to  METRIC 
From  multiply by  To get 
square feet  0.0929  square meters 
square yards  0.8361  square meters 
square miles  2.59  square kilometers 
METRIC  to  CUSTOMARY 
From  multiply by  To get 
square kilometers  0.3861  square miles 
hectares  2.4710  acres 