How to find the perimeter of a parallelogram - High School Math
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ABCD is a parallelogram. BD = 5. The angles of triangle ABD are all equal. What is the perimeter of the parallelogram?
ABCD is a parallelogram. BD = 5. The angles of triangle ABD are all equal. What is the perimeter of the parallelogram?
If all of the angles in triangle ABD are equal and line BD divides the parallelogram, then all angles in triangle BDC must be equal as well.
We now have two equilateral triangles, so all sides of the triangles will be equal.
All sides therefore equal 5.
5+5+5+5 = 20
If all of the angles in triangle ABD are equal and line BD divides the parallelogram, then all angles in triangle BDC must be equal as well.
We now have two equilateral triangles, so all sides of the triangles will be equal.
All sides therefore equal 5.
5+5+5+5 = 20
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A parallelogram, with dimensions in cm, is shown below. 
What is the perimeter of the parallelogram, in cm?
A parallelogram, with dimensions in cm, is shown below.
What is the perimeter of the parallelogram, in cm?
The triangle on the left side of the figure has a 
and a 
angle. Since all of the angles of a triangle must add up to 
, we can find the angle measure of the third angle:
Our third angle is 
and we have a 
triangle.
A 
triangle has sides that are in the corresponding ratio of 
. In this case, the side opposite our 
angle is 
, so
We also now know that
Now we know all of our missing side lengths. The right and left side of the parallelogram will each be 
. The bottom and top will each be 
. Let's combine them to find the perimeter:
The triangle on the left side of the figure has a
Our third angle is
A
We also now know that
Now we know all of our missing side lengths. The right and left side of the parallelogram will each be
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Find the perimeter of the following parallelogram:
Find the perimeter of the following parallelogram:
The formula for the perimeter of a trapezoid is:
,
where 
is the length of the base and 
is the length of the edge.
Opposite sides of a parallelogram have the same length. Therefore, both edges are 
and both bases are 
.
Plugging in our values, we get:
The formula for the perimeter of a trapezoid is:
where
Opposite sides of a parallelogram have the same length. Therefore, both edges are
Plugging in our values, we get:
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Find the perimeter of the following parallelogram:
Find the perimeter of the following parallelogram:
The formula for the perimeter of a parallelogram is:
where 
is the length of the longer side and 
is the length of the shorter side.
Plugging in our values, we get:
The formula for the perimeter of a parallelogram is:
where
Plugging in our values, we get:
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Find the perimeter of the following parallelogram:
Find the perimeter of the following parallelogram:
The formula for the perimeter of a parallelogram is
.
Plugging in our values, we get:
The formula for the perimeter of a parallelogram is
Plugging in our values, we get:
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