Question

The csa of a cylinder is 154cm2 . the tsa of this cylinder is 3 times its csa . find the radius of the cylinder

Answer 1

Hi.

Good question...Keep Progressing...

Here is your answer---

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Given---
 
Curved Surface Area of the Cylinder{C.S.A} = 154 cm^3
   
    Also, Curved surface Area of the Cylinder = 2 x pie x r x h

Thus,
             2 x pie x r x h = 154  ----------------------------------------------eq(1) 

According to the question,

 Total Surface Area of the Cylinder{T.S.A.} = 3 x Curved Surface Area
                                                              T.S.A. = 3 x C.S.A.
   We now,
 T.S.A. of cylinder = 2 pie x r(h +r) 

  Thus,  2 pie x r(h+r) = 3 x 154
     2 pie r h + 2 pie r^2 = 462

Using eq(1),
      154 + 2 pie r^2 = 462
              2 pie r^2 = 462 - 154
    2 x (22/7) x r^2 = 308
                       r^2 = 7 x 7
                        r = √49
                        r = 7 cm.
               ----------------------------
               ----------------------------

Thus, radius of the Cylinder is 7 cm.

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Hope it helps.

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