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The radius and height of a cone are in the ratio 4 : 3. The area of the base is 154cm2. Find the area of the curved surface.

Answer :

ATC

So lets begin with the ratio,-
let radius=4 x
and height =3 x

i,e.  r/h = 4 x/3 x-----------------------------(2)

(slant height) l=root of (4 x)square+(3 x)square ------------------------------(2)                                                                                            -Pythagoras therom
                                                                                                       {see fig.17 }

area of base=pie r square
154=22/7*(4 x)square
154=22/7*16 x
x=1.75

substitute x:-
radius=7 cm
height= 5.25 cm
slant height= 8.75 cm
CSA of cone= pie*r*l------------------------(3)
                      =22/7*7*8.75
                      =192.5 cm
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smjothibasu

Answer:

So lets begin with the ratio,-

let radius=4 x

and height =3 x

i,e.  r/h = 4 x/3 x-----------------------------(2)

(slant height) l=root of (4 x)square+(3 x)square ------------------------------(2)                                                                                            -Pythagoras therom

                                                                                                      {see fig.17 }

area of base=pie r square

154=22/7*(4 x)square

154=22/7*16 x

x=1.75

substitute x:-

radius=7 cm

height= 5.25 cm

slant height= 8.75 cm

CSA of cone= pie*r*l------------------------(3)

                     =22/7*7*8.75

                     =192.5 cm

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