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Current time:0:00Total duration:3:04

Finding missing side when given area

CCSS.Math: ,

Video transcript

the picture has an area of 80 square centimeters what is the width of the picture so here's our picture the superfun giraffe listening to music and our pictures shape is a rectangle and we're asked to find the width of that rectangle well maybe we don't know a special formula or a special equation to find width but we do know one to find area of a rectangle so let's use that formula and see how it can help us we know that area of a rectangle can be found by multiplying the length of the rectangle over here the length times the width so if we multiply the two side lengths of a rectangle we get its area and on this picture in this rectangle we are told that our area is 80 square centimeters so we already know the area and we can use that to help us we also know the length we're told that this distance from here to here this length is 10 centimeters so the length is 10 times the width we don't know the width that's what we're looking for so what we do know though is that we need our width to be a number that when it's multiplied times 10 we get 80 for an answer so what number times 10 equals 80 is 8 8 times 10 equals 80 so that means the width of our picture is 8 centimeters let's try one more a rectangle has an area of 24 square meters the width of the rectangle is 4 meters what is the length of the rectangle so this time we don't even have a picture to look at but we have enough information up here to solve this again we can use our formula that tells us area of a rectangle is the length times the width now we could draw this rectangle it might be helpful to visualize it but I'm going to show you here we can actually solve it without ever even seen the rectangle because we know that area is 24 square meters so the space the rectangle covers is 24 square meters and the length we don't know the lengths were asked what is the length but we do know that the width is 4 meters so our length has to be some number that when it's multiplied times 4 we get 24 for the answer and that number must be 6 because 6 times 4 equals 24 so the length of our rectangle is 6 and in this case we're talking about meters meters