hi it's Ashley and I am excited to be doing some more geometry with you today
we're going to start learning how to measure shapes with perimeter you ready
let's go
what is perimeter you might ask perimeter is the distance
all the way around a shape and to find perimeter what we need to do is add up
the lengths of all sides of a shape so here you can see that we have a
rectangle and this rectangle has a length of six inches and a width of two
inches now a lot of times you might see a shape like this where only some of the
sides are labeled so in this case we have six inches here and two inches here
now what that means is the opposite side that is not labeled is going to be the
same so this one here should be two and this one down below should be six okay
so we're going to start by adding the top and the bottom of our rectangle six
inches that's a double so if you know those six plus 6 is equal to 12 and then
our left and right side two plus two is equal to four now we just need to add 12
and four so 12 plus four is equal to 16 16 1/16 inches
and that is our perimeter I'm going to put a P for perimeter P equals 16 inches
and box that answer okay now let's look at finding the perimeter of a triangle
this time all of our sides are labeled we have five inches four inches and
three inches they're on the bottom so we just need to add up all three of those
numbers five four and three inches all the way around gives us five and four is
nine three more makes 12 inches so our
perimeter is equal to 12 inches and let's box that answer look at this one
this here is a word problem and it doesn't give us a shape to look at so
what do we do well let's read it says find the perimeter of a rectangle with a
length of two feet and a width of four feet so what should we do what we should
do here is draw a picture I'm going to draw my rectangle and I know I have as 2
feet by 4 feet all right both sides across from each
other are the same so two plus two is equal to four and four plus four is
equal to four these eight now let me add my four plus eight and I get a total of
twelve feet my perimeter is equal to 12 feet and that's it you just learned
perimeter finding the distance all the way around a shape now be sure you go
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