So it’s not just triangles that have
A: No, not at all. The perimeter of a
shape is basically the edge around the
outside of a shape, whether it’s a triangle,
rectangle, parallelogram, or some other
Are there any shortcuts we can
take in calculating the perimeter of a
A:It all depends on the shape.
You calculate the perimeter of a shape by
adding the lengths of all its sides together.
You can take a few shortcuts if some of
these sides are the same length.
As an example, a square has four sides that
are all the same length, so the perimeter of
a square is just 4 times the length of one
What about for a parallelogram?
A:A parallelogram has two pairs of
congruent sides, so there are two unique
side lengths. You can find the perimeter of
a parallelogram by adding these two unique
side lengths together, and then multiplying
What if two shapes have the same
area and the same perimeter? Does this
mean they’re the same shape?
A:Not automatically, no, you need
more information. Many different shapes
can have the same area and the same
More information? Like what?
A:Well, a good starting point is if you
know what sort of shapes you’re dealing
with. This will tell you how many sides your
shapes have, and how many of these are
As an example, if you’re told you have two
squares and they both have the same area,
the squares must be congruent. This is
because you calculate the area of a square
by calculating (side length)
. The only way
the squares can have the same area is if
their sides are the same length.
In general, if you know what type of shape
you’re dealing with, you can use the
properties of the shape to help you deduce
A parallelogram is a four-sided shape Consecutive angles of a
whose opposite sides are parallel to parallelogram are supplementary.
To calculate parallelogram area,
Opposite sides of a parallelogram multiply the width by the height:
To calculate parallelogram perimeter,
Opposite angles of a parallelogram add together the length of each side.
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