Added: 3 years ago
From: msumurph
Views: 7,638
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  • thanks for the video but in the last steps you lost me when the X^2 disappeared from the right-hand side formula. You introduced an r^2 to both sides all of sudden.

    Plus how you made the last bracket Positive isnt all good. All good.

    All you kids need to no is anti derivatives, integration i suggest this video watch?v=TospO7-aoiw

  • your r kinda looks like an n

  • Nice Job

  • can you please tell me how did you find the value of y^2 ?? You kinda jumped without explaining that

  • @SuperSurreptitious The cross-section is a circle with radius y. The area of the cross section is pi*y^2. Then we write the y^2 in terms of x.

  • ty very much that was very helpful

  • HOLY SMOKES, you saved me, that was SO helpful!

  • @juicywednesday Glad it helped!

  • @msumurph Hello! I understand the method of slicing to find the volume of the sphere. But, I cannot extend the same to find the surface area of the sphere (The incorrect solution is pi^2*r^2). Although I was able to find the correct surface area (taking infinitesimal length of arc 'ds' instead of 'dx'), I am not able to understand:

    1. Why use 'dx' to get sliced area Ax = 2*pi*y*dx and 'not' use 'ds' to get sliced area Ax = 2*pi*y*ds?

    2. Why use 'ds' to get sliced circumference Cx = 2*pi*y*ds?

  • @msumurph By the way, ds = sqrt[(dy)2+(dx)2] = dx*sqrt[1+(dy/dx)2]

  • thanks man! this is a great help!

  • Man, you're LAME. You like stuck for 10 times.

  • @Diemedes

    Your RUDE.

    And this video is AWESOME!

    Lots of help if only I had seen it before the test...that rude kid is just jealous of your mad math skills. Trust me.

  • @lemongrassmari

    Okay, perhaps I was a little harsh on him. But that still doesn't mean it took him an auwful lot of time to find the volume of a sphere with what probably is the easiest way of calculating it.

  • @Diemedes

    I was a little rude too...sorry. But you need to remember that most of the people who make these kinds of are making them out of the kindness of their hearts, so while perhaps this did not help you, it did not hurt you since all the information is correct. Plus, it helped others. So if you want nice people to continue to make these kinds of videos for us then I think it would be best to either be supportive or give CONSTRUCTIVE criticism.

  • TAURUSES!!!!!!!!!!!!!!

    AHHHA NOOO!

    I should fail the bc exam to retake and ace calc1 in college

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