Answers

2016-02-28T15:51:55+05:30
Curved surface area of cylinder = 2πrh
1320 cm²                                     = 2 ×22/7 × rh
1320 × 7/2×22 ×r                        = h
210/r                                            = h

volume of cylinder                      = πr²h
3960                                            = 22/7 ×r² × 210/r
3960 ×7/22×210                          = r²/r
6 cm                                              = r

so the radius is 6 cm
 
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2016-02-28T21:26:00+05:30
The curved surface area of the cylinder is 2πrh
then 
2πrh = 1320
2×22/7×rh = 1320
h = 1320×7/22×1/2
h = 210/r

then the volume of the cylinder is πr²h

πr²h = 3960
22/7×r²×210/r =3960
r²/r = 3960×7/22×210
r = 6
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