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 April 22nd, 2013, 03:10 AM #1 Newbie   Joined: Apr 2013 Posts: 3 Thanks: 0 Help with relationship between circle and cone Hi all, I'm a bit stuck with how to work with mainly unknown variables to solve this question… I'm supposed to find the radius 'r' of the base of the cone, the height 'h' of the cone and the angle ø of inclination of the cone in degrees when: (a) $\theta= \pi$ and (b) $\theta= \frac{\pi}{2}$ Here is a diagram of the circle and cone I'm working with: http://i.imgur.com/NeVW4db.png Not exactly sure how to approach the question...
 April 22nd, 2013, 04:08 AM #2 Global Moderator   Joined: Dec 2006 Posts: 20,921 Thanks: 2203 Can you find h and r in terms of R on the assumption that the length of the solid circular curve in the first figure is the same as the perimeter of the base of the cone in the second figure?
 April 22nd, 2013, 04:26 AM #3 Newbie   Joined: Apr 2013 Posts: 3 Thanks: 0 Re: Help with relationship between circle and cone Not really. I do understand that the solid sector circumference is the cone's base circumference. Not sure of the formulae that I apply to find the other variables though :S
 April 22nd, 2013, 04:50 AM #4 Global Moderator   Joined: Dec 2006 Posts: 20,921 Thanks: 2203 What formulas do you know for the two circumferences? What does equating them tell you?
 April 22nd, 2013, 06:58 AM #5 Newbie   Joined: Apr 2013 Posts: 3 Thanks: 0 Re: Help with relationship between circle and cone After much long working out, I've managed to get parts (a) and (b) done. Still a bit stuck on ( c ) - not exactly sure what it's asking. But apparently it should be a general form of (a) and (b)… Task sheet - http://i.imgur.com/PbN6Wx8.png
 April 23rd, 2013, 07:01 AM #6 Global Moderator   Joined: Dec 2006 Posts: 20,921 Thanks: 2203 Your images are no longer available.

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