How To Calculate Surface Area
In this video, Charles, a math teacher, explains the basics of surface area, and then teaches how to easily calculate surface area by using subtraction. This method will help you to successfully complete practical exam questions such as finding the area of a garden.
Hi, my name is Charles and I'm one of the Math teachers from the Maxim workshop. I'm just going to now teach you how to do some Math. In this video, I'm going to show you how to calculate surface area.
Now, surface area is a measurement or quantity that has two dimensions and that basically means you have a length or you have a height, or you have a length and you have a width. Now, commonly you would find the units of surface area denoted as meters squared, and kilometers squared, and centimeters squared. It's basically this number 2 here that tells you that you have two dimensions.
So, that relates to meters, a length, and you multiply by a length. Just do it like that. So, obviously if you're measuring a length, you would only have meters.
If you're measuring surface area, then you would have this number 2 placed up on your meters. If you're measuring cubic area, which is basically a volume, then you would have a number 3. So, that would be a length times width times height.
Now, the classic case "m" relating to surface area is in an exam question, something like a garden. They want to know how much material that might be laid over that garden. Even for a carpet, you would need to know surface area.
This is the picture of the garden. We have an isolated area over here, which might be a sandpit. You've got this area here which is the house.
Our focus is really the garden here, the total garden which is outlined by the blue line. If we look at the total surface area of the garden, that information might be provided. You have something like 100 meters squared.
Now, imagine if they provided you with lengths or the second smaller area within the garden, which might be your sand pit. We'll note this side as 5m and this as 6m. Now what they were interested in for this particular question is what were the lengths of this area and this area.
Now, the first thing you would need to know is your equation for calculating areas. Now, that again is just basically length times width. For B, we can make a valid calculation about this because we have the lengths and we have the widths.
For A, the area of B is equal to 5 meters times 6 meters. All we have to do is multiply the numbers together, and of course multiply the units together, which is here. 5 times 6 is 30 and m times m is meters squared.
So, this gives us the area of B. Again, we want to find the area of A. Now, if you look at the total area, it is given as 100 meters squared.
So, if you wanted to find A, this area here, subtracting the sandpit, then obviously, you would look at this area which is the total area, and then just subtract B, which is your sandpit area. That would actually leave you with the remaining area, which is A. The area of A is equal to 100 meters squared, subtracting 30 meters squared.
That leaves us with 70 meters squared. Again, just a recap. Area is calculated by length times width, but as you can see in this question, sometimes you can make minor subtractions just like this one for the calculation of A by just subtracting the smaller section, which is B, from the total section.
That can also calculate the area of the shape that is A. So, that is how to calculate surface area. .