ShmoopTube

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have you ever heard of de ja vu it's a feeling that you're

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experiencing something that you've already experienced before have you ever [Dino thrashing and falling to the ground]

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heard of deja vu it's the feeling that you're experiencing something that

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you've already wait hang on a second anyway this video might just give you a

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serious case of deja vu because you're going to take another look and how to [a boy using his laptop while using a cellphone]

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find missing numbers related to areas and perimeters yep we know how to

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[lots of people dancing in a street] have a good time so let's take a look at this rectangle to find its area all we

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need to do is multiply its length by its width so we'd multiply 9 inches by 3

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inches to find 27 square inches easy stuff what about this one here we know [image of rectangle showing the length and width]

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the length of one side and the area but not some lace on the other side is there

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any way to find the length of that missing side will give you a hint even [Coop nodding his head to Dino]

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the best magnifying glass isn't going to help you better to just do some math

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[Sherlock Holmes using a magnifying glass on the rectangle] rather than play Sherlock so let's think back to the formula for the area of a

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rectangle the area of a rectangle is equal to its length times its width we

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know that it's area is 12 square inches and its length is 4 inches so the width has

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to be a number that when multiplied by 4 gives us 12 if we remember our

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[1 through 10 animal themed multiplication tables] multiplication tables we know there's only one number that does that three so

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the rectangle has a width of 3 inches you didn't even need a magnifying glass

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you can do a similar process of perimeters take a look at this rectangle we know

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that two sides are each 10 inches long and that it has a total perimeter of 30 [rectangle of 10 inch sides on a chalkboard]

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inches but what are the lengths of the remaining sides let's take a look at our

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formula for the perimeter it's what we get when we add up the length of the

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side we know that the perimeter is 30 inches and the two sides are 10 inches [Formula for finding out the length of the two unknown sides of the rectangle]

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long plus since the other two sides are opposite sides of a rectangle they're in

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the same length but what is that length we could try six inches unfortunately

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when we add those links up we get 32 inches not 30 and have you ever been on [a rollercoaster ride in descent]

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a roller coaster with a minimum height of 32 inches you know that 30 inches

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is definitely not the same to 32 inches sorry bud so let's try something slightly [kid not tall enough to go on the ride walks away]

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smaller like five inches we're in luck this map actually works out so the

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remaining slides are each 5 inches long unfortunately that short kid isn't quite [short kid trying to deceive the rollercoaster employee wearing a big clown wig]

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so lucky and even a really tall wig is I'm going to help the chances of getting

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on that roller coaster double sorry bud

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