
Area of a parallelogram
The number of square units it takes to completely fill a parallelogram.
Formula: Base × Altitude
Try this Drag the orange dots to move and reshape the parallelogram. Drag point D to change the base.
Area formula
The area of a parallelogram is given by the formula
where
b is the length of any base
a is the corresponding altitude
See Derivation of the formula.
Recall that any of the four sides can be chosen as the base. You must use the altitude that goes with the base you choose.
The altitude (or height) of a parallelogram is the perpendicular distance
from the base to the opposite side (which may have to be extended). In the figure above, the altitude corresponding to the base CD is shown.
Things to try
 In the figure above, click on "hide details"
 Drag the orange dots on the vertices to make a randomsize parallelogram.
 Estimate the area of the parallelogram just counting the squares inside it
 Calculate the area using the formula
When you done, click "show details" to see how close you got.
Other polygon topics
General
Types of polygon
Area of various polygon types
Perimeter of various polygon types
Angles associated with polygons
Named polygons
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