Find the surface area of a cone with a radius of 8in. and a height of 7 in.
I forgot the formula how to work this out can somebody help me. Thanks
Google can be a student's best friend. <g>
http://www.google.com/#q=surface+area+of+a+cone
SA = Lateral Area + Base Area
SA= (pi X radius X slant height) + (pi X r^2)
To find the slant height, use the Pythagorean Theorem.
Let me know if you need more help, it is no trouble at all :)
so the answer is 467.232 ???
A=πr(r+(√h^2+r^2))
Square root line continues at the top of h^2 through r^2. r is radius and h is height for this problem.
Now substitute numbers for the variables.
A=π8(8+(√7^2+8^2))
Now solve.
The rest I will leave up to you.
I hope this helps! :)
I still don't understand how to right it down to show my work. Please right it out for me thanks.
The part in the division is what's confusing me,.
This is what I get.
3.14*8(8+√49+64
25.12(8+√113
25.12+14.125
=39.245
I know I'm wrong
Callie, you don't need division I believe.
Multiply pi by the radius and that by the slant height. That counts as the lateral area. Then multiply pi by the radius-squared. Add those together.
Remember the slant height is not the same as the height, so use the Pythagorean Theorem to get this. :)
Hope this helps :)
What is the slant height? Or that them your talking about? Can't you just tell me the slant height?
The slant height would be 10.63014581, or rounded to 10.6 or even 11. Sorry, I thought you knew about the Pythagorean Theorem (a^2 + b^2 = c^2). :(
Anyways, hope this helps ;)
Callie could have used the formula I posted for her.
A=πr(r+h2+r2)
Very true Ms. Sue :)
You don't need to do division. You may be getting confused with the square root sign.
Well, 3.14*8(8+√49+64) is correct. However, you don't need to combine the numbers outside the parentheses just yet. This is because Parentheses comes first in PEMDAS. You must do everything inside the parentheses before you do anything else.
So, you would have 3.14*8(8+√113).
Next you simplify √113.
√113 = 10.630145812734649407999121914929 or 10.6
Now add what's in the parenthesis.
(8 + 10.630145812734649407999121914929) = (18.630145812734649407999121914929) or (18.6)
Now you should have: 3.14*8(18.6).
Next, you Distribute.
8 * 18.6 = 148.8
Now multiply by 3.14.
148.8 * 3.14 = 467.232
Also, Anonymous, I believe you were confusing Callie about the Pythagorean Theorem. Were you meaning about the "r^2 + h^2"? The Pythagorean Theorem is basically r^2 + h^2 in the formula I believe.
For example,
a^2 + b^2 = c^2
r^2 + h^2 = c^2
Basically, you just solve like you have done like the other problems with the Pythagorean Theorem, Callie at this point, but with r^2 + h^2 instead.
I hope this helps! :)
It's pretty easy, it's just that you have to remember the order, and formula to use(including the Pythagorean Theorem), Callie. Once you remember those, it can help you with other problems like it.
Also, it took me a while to make the above post, so I am sorry if I have been posting a lot later than what you, Anonymous, and Ms. Sue were talking about. I tried posting as fast as I could, but I had to focus on my own schoolwork.
I'm sorry, and I think I might have killed this thread. :p