29- If the volume and surface area of a sphere are numerically equal then its radius is-.(a) 2 units (b) 3 units (c) 4 units (d

Question

29- If the volume and surface area of a
sphere are numerically equal then its radius
is…..(a) 2 units (b) 3 units (c) 4 units (d) 5
units​

in progress 0
Mia 1 month 2021-10-26T11:17:32+00:00 2 Answers 0 views 0

Answers ( )

    0
    2021-10-26T11:18:54+00:00

    Answer:

    \bigstar{\bold{Option\:b:3\:units}}

    Step-by-step explanation:

    \Large{\underline{\underline{\bf{Given:}}}}

    • Volume of a sphere = Surface area of sphere

    \Large{\underline{\underline{\bf{To\:Find:}}}}

    • The radius of the sphere

    \Large{\underline{\underline{\bf{Solution:}}}}

    → First we have to find the volume of the sphere.

    → Volume of a sphere is given by

    Volume of a sphere = 4/3 × π × r³—–(1)

    → Now we have to find the surface area of the sphere

    → Surface area of a sphere is given by

      Surface area of a sphere = 4 π r²——(2)

    → By given we know that

      LHS of equation 1 and 2 are equal, hence RHS must also be equal.

      4/3 π r³ = 4 π r²

    → Cancelling 4 , π and r² on both sides

       1/3 r = 1

             r = 1 × 3

             r = 3 units

    → Hence the radius of the sphere is 3 units

    \boxed{\bold{Radius=3\:units}}

    → Hence option b is correct

    \Large{\underline{\underline{\bf{Notes:}}}}

    →Volume of a sphere = 4/3 × π × r³

    →  Surface area of a sphere = 4 π r²

    0
    2021-10-26T11:19:13+00:00

    Answer:

    3

    Step-by-step explanation:

    its easy

    (4/3)πr³=4πr²

    (4/3)r=4

    1/3r = 0

    r=3

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