1. Geometry: Areas of parallelograms
Chapter 9.1A
Geometry: Areas of parallelograms

2. What is a parallelogram?
Parallelograms look like rectangles that are falling over (actually rectangles and squares technically ARE parallelograms, just with special names!)

3. Area of a parallelogram
Parallelograms have the same formula for AREA as rectangles and squares.
A = b x h H E I G T
BASE H E I G T
The height is perpendicular to the base, NOT the slanted line!!!
BASE

4. Some heights are outside the shape, so be careful!
4.2 in
7 in.
6 in.
7.3 in.
8 in.
ALWAYS write the formula, then plug in the numbers!
A = b x h
A = 4.2 x 7.3
A = b x h
A = 8 x 6
A =
30.66 in2
A = 48 in2
Area is always labeled in “square” measures

5. Why Square Units? Height = 4 units Base = 8 units
Square units means how many squares fit INSIDE the shape!
Height = 4 units
Base = 8 units

6. Working backwards A = b x h 96 = 12 x h A = 96 ft2 h
Since we know the AREA already, work the problem backwards to find the height!
A = b x h
96 = 12 x h
h = 8 ft.
96 ÷ 12