Mathematics
13 Online
OpenStudy (anonymous):
Find the volume of the cone. (Round to the nearest tenth.)
Answer
1250.7 mm
2014.1 mm3
289.4 mm3
1229.4 mm3
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OpenStudy (anonymous):
OpenStudy (anonymous):
The formula you should use is \[V_{cone}=\frac{1}{3}\pi r^2 h\]
OpenStudy (anonymous):
radius is not clear
OpenStudy (anonymous):
i think it's 38
OpenStudy (anonymous):
There's a curvy arrow beside the 38, maybe it's circumference of the base?
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OpenStudy (anonymous):
is 38 the radius ?
OpenStudy (anonymous):
yes
OpenStudy (anonymous):
So \(C=2 \pi r\) first, and then the formula above, assuming 38 is the circumference. That would make the drawing more to scale as well.
OpenStudy (anonymous):
so whats the answer
OpenStudy (anonymous):
What part did you get stuck on?
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OpenStudy (anonymous):
finding the answer
OpenStudy (anonymous):
Your first task is to find the radius. If you're given a circumference of 38, then you can find the radius with \(C=2 \pi r\).
OpenStudy (anonymous):
238.64
OpenStudy (anonymous):
but thats not an answer
OpenStudy (anonymous):
Hrm, my radius was much smaller than that. Could you post your calculation?
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OpenStudy (anonymous):
2x3.14x38
OpenStudy (anonymous):
2*3.14*r = 38
OpenStudy (anonymous):
r = 38/6.28
OpenStudy (anonymous):
Where did that 14 come from?
Perhaps we should rearrange the equation first \[C=2 \pi r <=> r=\frac{C}{2\pi}\]
OpenStudy (anonymous):
?
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OpenStudy (anonymous):
If \[r=\frac{C}{2\pi}\] you just need to put 38 in for C, and find the value of the fraction.
OpenStudy (anonymous):
59.66?
OpenStudy (anonymous):
So you took 38, and divided it by 2\(\pi\), and got 59.66?
OpenStudy (anonymous):
yes
OpenStudy (anonymous):
but its wrong
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OpenStudy (anonymous):
im getting really confused
OpenStudy (anonymous):
The value of 2\(\pi\) is about 6.28, so if you divide 38 by 6.28, the number you get out should be smaller than 38.
OpenStudy (anonymous):
19
OpenStudy (anonymous):
nope
OpenStudy (anonymous):
That's 38 divided by 2. Divide that by \(\pi\)
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OpenStudy (anonymous):
6.05
OpenStudy (anonymous):
yup
OpenStudy (anonymous):
Alright, now we're getting somewhere! Now you need to use the equation for the volume of a cone: \[V=\frac{1}{3}\pi r^2 h\]
OpenStudy (anonymous):
344.79
OpenStudy (anonymous):
yea
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OpenStudy (anonymous):
so how do we get the answer
OpenStudy (anonymous):
1/3*3.14*(6.05)^2*9
OpenStudy (anonymous):
but thats nott the answer
OpenStudy (anonymous):
344.79 should be the answer, but for some reason it's not on the list you gave. I'm quite stumped.