Basic geometry and measurement
Sal figures out the width of a dog pen. Created by Sal Khan.
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- How would you figure the area of a pentagon?(79 votes)
- hey i need votes plz vote i will vote whoever votes me.(24 votes)
- Aaand that's what you get for not specifying which kind of vote! Seriously though, it's cringe to beg for upvotes. Especially on an otherwise blank comment that isn't even relevant to the video. You know, the GEOMETRY LESSON that this is the comment section for? If you want upvotes, post something that actually deserves them by virtue of being a legitimately commendable addition to the topic. Goodbye and have a nice day!(3 votes)
- Lisa built a rectangular flower garden that is 4 feet wide and has a perimeter of 26 feet.(12 votes)
- First, you multiply the width by 2. The product is 8. Next, you subtract 8 from the perimeter which is 26, and the difference is 18. Afterwards, 18/2 = 9. This means that 9 is the length. If you want to figure out the area, just multiply 4 and 9, and the product is 36 feet squared.(15 votes)
- Please vote
I need badges(19 votes)
- Aaand that's what you get for not specifying which kind of vote! Seriously though, it's cringe to beg for upvotes. Especially on an otherwise blank comment that isn't even relevant to the video. You know, the GEOMETRY LESSON that this is the comment section for? If you want upvotes, post something that actually deserves them by virtue of being a legitimately commendable addition to the topic. Goodbye and have a nice day! (Good luck with the badges BTW.)(1 vote)
- How to calculate depth?(11 votes)
- Depth is not something that you would calculate so much as you would just measure it. You would need a starting place - something like sea level (the surface of the sea), then you would just measure down to the bottom to find depth.(15 votes)
- Is there another way of doing this?
For example, what I learned was 78/2 and then take that answer and subtract by the one length that the problem gives you, because the formula that I learned was 2(L+W).
And also, which is the fastest and easiest way of doing this??(14 votes)
- *What if they don't give you the length? And they just give you the area and height?*(14 votes)
Mike built a rectangular dog pen that is 21 feet long and has a perimeter of 78 feet. What is the width of Mike's dog pen? So let's draw what it might look like. So it might look something like this. I'll do my best to draw it, a rectangle or potential dog pen. So let's say that this is the dog pen right over here. And they give us its length. Its length is 21 feet. So this distance right over here is 21 feet. And of course, if that distance is 21 feet, this distance is also going to be 21 feet. Now, they also tell us that the perimeter is 78 feet. So the perimeter is 78 feet. So we need to figure out the width. And the width would be this length-- or this width, I should say-- this width, which is going to be the same thing as that width right over here. So let's think about. And we know how we figure out the perimeter. If we added this distance, 21 feet, to this distance, the width, plus 21 feet to the width again, we're going to get to 78 feet. So one way to back into what the width is is to say, well, look if we sum up all of these lengths, we're going to get 28 feet. So let's at least subtract these two orange lengths, the two 21 feet, from the 78 feet. And then we figure out how much length essentially these two widths have to make up. So let's subtract. Let's do 78 minus 21 minus 21. And what's that going to be equal to? So that's 78 minus 42. And 78 minus 42-- I don't want to make a careless mistake-- 78 minus 42 is going to get me to 36. So this is equal to 36. And let's remind ourselves what 36 feet is. That's the total length-- or I should say the total width-- if we were to take the width down here and add it to the width up here. Now, we know something else. These are the exact same width, that this distance is the same as this distance. And if we add them together, we get to 36. So what are two distances, or what are two numbers that I can add together to get to 36? Well, we know that 18 plus 18 is equal to 36. So this one down here must be 18. And this one up here must also be 18. And we can verify that. Try adding all of these up together. You add the two widths. You get 18 plus 18. And you add the two lengths, plus 21 plus 21. And you are left with 36, which is exactly what we got here. This is what we needed the two widths to add up to-- plus 42. Which is, of course, equal to-- 36 plus 42 is equal to 78, which is the perimeter.