How to Find the Surface Area of a Rectangular Prism Math with Mr J

Welcome to Math with Mr. In this video, I'm going to cover how to find the surface area of rectangular prism. And remember, when it comes to surface area, simply put, it's the total area of the outside part or layer of 3D figure. So, when it comes to rectangular prisms, they have six faces. So, we need to find the area of each face and add all of that up in order to get the surface area. Now, at the top of your screen in blue, we are going to use that formula there in order to find the surface area of rectangular prism. So, surface area equals 2 * front or back + 2 * right or left + 2 * top or bottom. So, let's talk about what that means. Now, have everything multiplied by two because, for example, if we pick the front or back, let's say we pick the front here. If we find the area of the front, we can multiply that by two because the back is the exact same as the front. Same with right and left. We can find the area of the right face and then multiply it by two because the left is the exact same as the right. Same with top and bottom. So, let's get into finding the surface area here and we'll start with surface area equals two and we need to find the area of the front or back. So, let's find the area of the front where we have six by two. So, we can do area equals length * width for rectangle. Plug in area equals 6 * width of two and we get an area of 12 square inches for the front. So, we could plug in 12 here. Plus, now we need to do the right and left. Now, but before get to that, want to mention to the right here, have net of that rectangular prism. So, basically, unfolded it so you can see all of the faces and it's not in 3D form. So, it kind of lays everything out so we can visualize what we're doing little better. So, as of right now, we have 12 square inches here for the area of the front and the back. So, let's do right and left. So, we'll pick the right side here, the right face, and we have three by two. So, area equals length * width. So, we can plug in 3 * 2 and that gives us an area of Let's actually write it out. Length * width. Area equals 3 * 2. So, that area is going to be 6 square inches. So, again, that's the right and left. So, we would do 2 * 6 for the right and left. And lastly, we need to do the top and the bottom. So, we're going to take look at the top where we have six by three. So, area equals length * width. Plug in 6 * 3 and we get an area of 18 square inches. So, our bottom is 18 square inches and our top is 18 square inches. So, we would plug in two * 18. Now, let's start solving. 2 * 12 is 24. 2 * 6 is 12 + 2 * 18 is 36. So, the top or I'm sorry, the front and back combined, we have an area of 24 square inches. The right and left combined area of 12 square inches and the top and bottom has combined area of 36 square inches. So, we have all of our faces included. Now, we just need to add everything together. So, surface area equals 24 + 12 is 36 + 36 gives us an answer of 72 square inches. So, that's the area of all of the faces added together. So, there you have it. There's how you find the surface area of rectangular prism. Again, find the area of each face and then add all of that together. hope that helped. Thanks so much for watching. Until next time, peace.