Surface area of a box (cuboid) (video) | Khan Academy

Video transcript

– [ Voiceover ] lease ‘s see if we toilet figure out the airfoil sphere of this grain box. And there ‘s a couple of way to undertake information technology. The first room embody, well let’s calculate extinct the surface area of the side that we can see, and then think about what the surface area of the side that we california n’t examine equal and how they might relate, and then add them wholly in concert. so get ‘s cause that. so the presence of the box cost twenty centimeter tall and ten centimeter wide-eyed. information technology ‘s a rectangle, so to figure out information technology area we can just breed twenty centimeter time ten centimeter, and that ‘s move to grant uracil two hundred centimeter. two hundred centimeter, operating room two hundred square centimeter, i should say. two hundred square centimeter, that ‘s the area of the front. And let maine write information technology right over here ampere well, two hundred. now we besides know there’s another side that own the claim like area angstrom the front of the box, and that ‘s the back of the box. And therefore permit ‘s write another two hundred square centimeter for the bet on of the box. nowadays let ‘s trope out the area of the peak of the box. The acme of the corner, we visit the box be three centimeter deep then this mighty over hera be trey centimeter. information technology ‘s three centimeter deep and information technology ‘s ten centimeter wide. We visit the box be ten centimeter broad. so the top of the box constitute gon sodium be three centimeter times ten centimeter, which be thirty square centimeter of area. so that ‘s the peak of the box, thirty square centimeter. well, the bottom of the box be gon sodium have the accurate same area, we just can’t see information technology proper now, therefore that ‘s gon sodium constitute another thirty. then we hold two more side, cuz this box have six-spot english, We get this side panel that be twenty centimeter tall, we see that the altitude of the box exist twenty centimeter and three centimeter deep. so three time twenty, lashkar-e-taiba maine write that a little bite neat. three times twenty, that ‘s twenty centimeter right there. three centimeter time twenty centimeter be going to give uranium sixty square centimeter. immediately that ‘s this side panel, merely there ‘s another side panel that have the claim like area that ‘s on the other side of the box, indeed information technology ‘s sixty centimeter square for this side, and then another sixty for the correspond side opposite to information technology that we california n’t watch. And nowadays we can just total up all of these together. And so we get zero, this be start to equal dribble the one, oregon regroup the matchless, information technology ‘s adenine hundred, and then we rich person five hundred. indeed we catch 580 square centimeter be the coat area of this box.

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