We learned how to find the volume of disks and washers.
There are two formulas in terms of x and y for each. If I memorize the formula, I won't be in any trouble.
But, there's one part that might be confusing: a radius.
Radii can be a function itself, but sometimes can be a function subtracted by another function.
The example is the picture at the bottom! But, if I look into it closely, I can easily find the radius!
Another tricky question was on #5 the chapter 7.3 quiz. There's a bounded area and we needed to find the volume of the area rotated around x=-1. Firstly, I did it in the same way I did around y-axis. And, I thought I got the right answer. But, a question arose. Why did Mr.Cresswell rotate it around x=-1? And, I found that I was supposed to add 1 to each function before being squared (because the short and long radii included 1 unit.) - hopefully, that sentence makes sense :)
After that, when I compared the two answers, there's some difference, but it was not like a simple number(such as fraction.), while I expected the second one would be larger by 8 than the first one. (Because the rectangle had a width of 2 and a height of 4.) I wondered why my guess was wrong. I found out I thought of the shape as 2-dimension shape. In reality, it is 3d shape, so I can't just add the area of the rectangle.
Overall, my participation was good. I did homework well and filled out CCC. This weekend, I am gonna rest! Have a great weekend!