Interactive
Geometry Dictionary
How Do You Find
the Area of a Triangle? To find the area of a triangle, find a way to make it look like something
simpler that you already know the area of. In the applet below, click the Make Copy button to make a copy of
the blue triangle. You can translate the green copy by using point D and you can rotate it using point F. See
if
you
can make a parallelogram using the triangle and its copy.
Use the First Move and Second Move buttons to show one way of making a parallelogram. There are also two
other ways - can you find them? What measurements on the triangle do you need to make in order to find the area
of the parallelogram?
What is the area of the triangle?
Answer:
Since two triangles make up the parallelogram, the area
of the triangle is one half the area of the parallelogram. You need to
measure the base and the height of the triangle since these are the same
as the base and the height of the parallelogram.
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Area of a triangle = 1/2
base times height
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Pre-K - 2 
