Before watching the lecture the only thing that I knew about was what Surface Area, Prisms, and Cylinders were. I somewhat know how to find it, but not really. This is all I knew before watching the lecture.
After watching the lecture I learned how to find the surface area of prisms and cylinders and how to find the lateral area of prisms and cylinders. To find the lateral area of prisms the equation is l=Ph, or the length equals the perimeter times the height. To find the surface area of a right prisms you use the equations S=2B+Ph, or the surface area equals two times the base plus perimeter times the area. To find the surface area of a cylinder you use the equations S=2B+Ch and S=πr^2+πrH, or the surface area equals two times the base plus the circumference time the height and surface area equals pie times radius squared plus pie times radius times height. You can use these equations to find lateral area of prisms and cylinders and surface area of prisms and cylinder, but you have to make sure you use the right equation because they are closely alike and if you don’t use the right one, your answer will be wrong. This is everything that I learned after watching the lecture.
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Questions:
I commented on Michelle K's blog and Adam B's blog.
For your first question, you need to find the diameter of your cylinder. 480pi is already given to us. The equations that you will use are S=2pirh+2pir^2. Then you need to plug your numbers into your equation, so you have...480pi=2pi(8)+2pirsquared...0=2pir2+16pir+-480pi. Then you can simplify your problem down more so it is easier to figure out so then you have. 0=2pi(r^2+8r+-240). When you plug it into your quadratic formula you have -8 plus or minus the square root of 64--4(1)(-240) divided by 2. You end up with a radius of 12 and to get your diameter you have to multiply by two. so you end up with D=24, which gives you D as your final answer.
ReplyDeleteGood job Amy. I will answer your second question. We are trying to find the surface area of this right cylinder, so we will be using the equation S=2πr^2+2πrh. We can then plug in the numbers we know. So our new equation is 925.2=2π(9.5)^2+2π(9.5)h. We can simplify this equation down to 925.2=180.5π+19πh. We can then subtract 180.5 pi from each side and we are left with 358.143=19πh. We can divide each side by 19π to get h by itself, so we are left with 6. H=6.
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