the curved surface area of a right circular cone is twice that of an other right circular cone. if the slant height of the second one is twicw that of the first cone, find the ratio of the radius of first cone to that of second cone.
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let r1 and r2 be the radius of 1st and 2nd cone respectively.
let L1 and L2 be the slant height of 1st and 2nd cone respectively.
We know, C.S.A of cone = πrl
According to question it is given that...
⇒ πr1L1 ÷ πr2L2 = 2/1
⇒ r1L1 ÷ r2L2 = 2/1.....................................(i)
∴ L2 = 2L1....................................................(ii)
Now, substituting equation (i) and (ii) and we get.
⇒ r1 * L1 ÷ r1 * 2L1 = 2
⇒ r1 ÷ r2 = 4/1
⇒ r1 : r2 = 4 : 1
let L1 and L2 be the slant height of 1st and 2nd cone respectively.
We know, C.S.A of cone = πrl
According to question it is given that...
⇒ πr1L1 ÷ πr2L2 = 2/1
⇒ r1L1 ÷ r2L2 = 2/1.....................................(i)
∴ L2 = 2L1....................................................(ii)
Now, substituting equation (i) and (ii) and we get.
⇒ r1 * L1 ÷ r1 * 2L1 = 2
⇒ r1 ÷ r2 = 4/1
⇒ r1 : r2 = 4 : 1
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