9.2 Outline

A.  Rectangles
      1.  define area
      2.  define square unit
      3.  formulas
           a. rectangle
           b. square
B. Parallelograms
      1.  definition
      2.  formula
      3.  derivation of formula
C. Triangles
      1.  formula
      2.  derivation of formula
D.  Trapezoids
      1.  definition
      2.  formula
      3.  derivation of formula
E.  Circles
      1.  formula
      2.  derivation of formula
F.  Acre
     1.  definition
     2.  conversio

9.2 Essential Ideas

Area  is the number of squares which will fit inside a given figure.

Some common area formula for area are:
rectangle; A = lw
square; A = s²
parallelogram; A = bh
triangle; A = (1/2)bh
trapezoid; A = (1/2)h(b + B)
circle; A = (pi)r²
acre; A = 43,560 ft²