## 8.2 Outline

- Rectangles
- define area
- define square unit
- formulas
- rectangle
- square

- Parallelograms
- definition
- formula
- derivation of formula

- Triangles
- formula
- derivation of formula

- Trapezoids
- definition
- formula
- derivation of formula

- Circles
- formula
- derivation of formula

- Applications
- conversion application
- acre definition
- conversion of acres to square feet

## 8.2 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 =s*

^{2 }parallelogram;

*A*=

*bh*

triangle;

*A=*(1/2)

*bh*

trapezoid;

*A*= (1/2)

*h*(

*b +B*)

circle;

*A*= π

*r*

^{2 }acre;

*A =*43,560 ft

^{2}