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vr0nvr0n
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Homework Statement
A sector with central angle θ is cut from a circle of radius R = 6 inches, and the edges of the sector are brought together to form a cone. Find the magnitude of θ such that the volume of the cone is a maximum.
Homework Equations
Volume of a Cone = ⅓ * π * r2 * h
Area of a Sector of a Circle = R2/2 * Θ
The Attempt at a Solution
So, this problem is a lot like other cone/volume problems I have done before, but I have never had to find the magnitude of Theta before.
Normally, I would use the Pythagorean Theorem to determine what to sub in for "r" in the Volume of a Cone equation (in this case, that would be 36-h2 = r which can be determined by using the Pythagorean theorem as R2 = r2 + h2. In this problem "R" always = 6).
I know I can use this information to determine the critical numbers of "h," but I can't seem to determine when the Area of a Sector of a Circle would come into play. It is related to "R," which is always 6 in this problem, so I determined that this equation could be simplified to 18*Θ.
I attempted a solution by finding the critical numbers as I mentioned above and plugged those into Θ, but that doesn't really make sense to me. Any guidance would be appreciated. I don't want to be given the answer, obviously -- This isn't the forum for that. But, any hint or clue would be amazing.
Thank you so much.