Question

any one knows the answer properly circle one...

Answer 1

Given,
Height of each cone= 3 cm
Total height= 13 cm
Radius= 4 cm
Now,
Surface area of model=
C.S.A.(Cylinder)+2*C.S.A.(Cone)
Now,
For cones:-
Slant height= √{(3)²+(4)²}
= √{9+16}
= √25= 5 cm
Now,
For cylinder:-
Height= 13-2*3= 13-6= 7 cm
Now,
C.S.A.(Cylinder)= 2πrh
= 2*3.14*4*7
= 175.84 cm²
Again,
C.S.A.(Cone)= πrl
= 3.14*4*5
= 62.8 cm²
Now,
C.S.A.(Modal)= 175.84+62.8
= 238.64 cm²

Hope this helps you!

Answer 2

Given :

radius of the model = 4 cm

height of each cone = 3 cm

height of the model = 13 cm

Curved Surface area of cylinder

height of cylinder = 13 cm - 3 cm - 3 cm

                              = 13 cm - 6 cm

                              = 7 cm

radius = 4 cm

Curved SA of cylinder = 2 π r h

                                     = 2 × 3.14 × 4 × 7

                                     = 56 × 3.14

                                     = 175.84

Curved Surface Area of 2 cones

Curved surface area = π r l

By Pythagoras theorem :

l² = 3² + 4²

==> l² = 9 + 16

==> l² = 25

==> l = 5

CSA = 2 × π r l

        = 2 × 3.14 × 4 × 5

        = 40 × 3.14

        = 125.6

Surface area of the model

SA of the model = 125.6 + 175.84

                           = 301.44

The surface area will be 301.44 cm²

Thanks !