And so the area of each of these 14 times 10, they are 140 square units. Now we can think about the areas of I guess you can consider It would be this backside right over here, but You can't see it in this figure, but if it was transparent, if it was transparent, So that's going to be 48 square units, and up here is the exact same thing. Thing as six times eight, which is equal to 48 whatever Here is going to be one half times the base, so times 12, times the height, times eight. Of this, right over here? Well in the net, thatĬorresponds to this area, it's a triangle, it has a base So what's first of all the surface area, what's the surface area We can just figure out the surface area of each of these regions. So the surface area of this figure, when we open that up, And when you open it up, it's much easier to figure out the surface area. So if you were to open it up, it would open up into something like this. Where I'm drawing this red, and also right over hereĪnd right over there, and right over there and also in the back where you can't see just now, it would open up into something like this. It was made out of cardboard, and if you were to cut it, if you were to cut it right The surface area of the prism is 2 0 4 u n i t .Video is get some practice finding surface areas of figures by opening them up intoĪbout it is if you had a figure like this, and if Where □ and □ are its two parallel sides and ℎ its height. Let us work out the area of the base of the prism. We can of course work out the area of each rectangular face individually and sum up all together we find the same result. Its area is given by multiplying its length by its width. We clearly see on the net that they form a large rectangle of length the perimeter of the base and width the height of the prism, The lateral surface area of the prism is the area of all its rectangular faces that join the two bases. Rectangle whose dimensions are the height of the prism and the perimeter of the prism’s base. The surface area of a prism: on the net of a prism, all its lateral faces form a large In the previous example, we have found an important result that can be used when we work out The surface area of the prism is 7 6 u n i t . t o t a l b a s e l a t e r a l u n i t To find the total surface area of the prism, we simply need to add two times the area of theīase (because there are two bases) to the lateral area. We do find the same area however we compose rectangles to make the base. We can of course check that we find the same area with adding the area of two rectangles Or as the rectangle of length 5 and width 4 from which the rectangle of length The base can be seen as made of two rectangles, We need to find the area of the two bases. Prism, which is given by multiplying its length by its width: Now, we can work out the area of the large rectangle formed by all the lateral faces of the The missing lengths can be easily found given that all angles in the bases are right angles. The width of the rectangle formed by all lateral faces is actually the perimeter of the base. Where □ and □ are the two missing sides of the base of the prism. They form a large rectangle of length 3 and width We see that all the rectangles have the same length: it is the height of the prism, On the net, the rectangular faces between the two bases are clearly to be seen.
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