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13. The ratio of the heights of two right cones having the same radius of the base is 6:5. Find the ratioof their (a) volumes and (b) curved surface areas, when each radius of the base is half the height ofthe shorter cone.?

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Dimension of bigger cone: h_1,l_1,r

Dimension of smaller cone: h_2,l_2,r

frach_1h_2=frac65

a) Ratio; of ; the ; volume ; =fracV_1V_2=fracprod 	imes r	imes h_1prod 	imes r	imes h_2=frach_1h_2=frac65

b)   l_1^2=r^2+h_1^2

      l_1^2=(frach_22)^2+h_1^2 ;;;;;;;;;;;;;;;;; (ecause r=frach_22)

      l_1^2=(frac56	imes2	imes h_1)^2+h_1^2

     l_1=frac1312	imes h_1

     l_2^2=r^2+h_2^2

     l_2^2=(frach_22)^2+h_2^2 ;;;;;;;;;;;;;;;;; (ecause r=frach_22)

    l_2^2=frac54 	imes h_2^2

    l_2^2=frac54 	imes (frac56	imes h_1)^2

    l_2=frac5 sqrt512 	imes h_1

    Ratio; of ; the ; C.S.A.=fracC.S.A._1C.S.A._2=fracprod 	imes r	imes l_1prod 	imes r	imes l_2=fracl_1l_2=frac 1312	imes frac125sqrt5=frac135sqrt5

 

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Deependra Verma

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