July 4th, 2018, 11:18 PM  #1 
Senior Member Joined: Nov 2010 From: Indonesia Posts: 2,000 Thanks: 132 Math Focus: Trigonometry  [ASK] Two Cones
Azis wants to make two cones using cartons. The surface area of the first cone is twice the second. The side length of the first cone is also twice the second. Determine the ratio of those cones' radius! s1 = 2s2 L1 = 2L2 πr1(r1 + s1) = 2πr2(r2 + s2) r1(r1 + 2s2) = 2r2(r2 + s2) I was stuck with quadratic equations... 
July 5th, 2018, 01:41 AM  #2 
Senior Member Joined: Aug 2012 Posts: 1,998 Thanks: 569  
July 5th, 2018, 04:48 PM  #3 
Senior Member Joined: Nov 2010 From: Indonesia Posts: 2,000 Thanks: 132 Math Focus: Trigonometry  
July 5th, 2018, 09:59 PM  #4 
Global Moderator Joined: Dec 2006 Posts: 19,502 Thanks: 1739  
July 5th, 2018, 10:04 PM  #5 
Senior Member Joined: Nov 2010 From: Indonesia Posts: 2,000 Thanks: 132 Math Focus: Trigonometry  
July 6th, 2018, 12:15 AM  #6 
Global Moderator Joined: Dec 2006 Posts: 19,502 Thanks: 1739 
According to Google's translator, "luas permukaan" means "surface area" (as distinct from "total surface area"). Although a more specific phrase is available, it's possible that the need for it was overlooked.


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