14.1 Areas of Polygons and Circles

 

Area on a Geoboard (or dot paper)

 

addition method: sum the area of the figure by finding the area of the smaller parts and then adding them together

 

Figure

 

a) b)

 

 

 

 

 

 

 

 

 

 

subtraction method: Figure

 

 

 

 

 

Examples

 

Figure a) and b)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Area of a Rectangle

 

Figure

Formula: A = lw

 

 

 

 

 

 

 

 

 

 

 

Example: Find the area of each rectangle (Figure a) and b))

 

 

 

 

 

 

 

 

 

 

 

 

 

Area of a Parallelogram

 

Formula: A = bh

 

 

 

 

 

 

 

 

Area of a Triangle

 

Formula: A = bh

 

 

 

Examples: Find the area for each (Figure)

 

a)      A = bh

 

 

b)      A = bh

 

 

c)      A = bh

 

 

d)     A = bh

 

 

e)      A = bh

 

 

 

Area of a Trapezoid

 

Figure

 

Formula: A = h (b1 + b2)

 

 

Examples: Figure

 

 

a) b)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Area of a Regular Polygon

 

Figure

 

Formula: A = ap

 

 

 

 

 

 

 

 

 

Area of a Circle

 

Figure

 

Formula: A =