AP EAMCET202120 Aug 2021Morning ShiftMathematicsApplication of DerivativesActual
If the radius of a sphere is measured as 9 cm with an error of 0 . 03 cm , then find the approximate error in calculating its surface area.
Options
- A2 . 16 π cm 2
- B21 . 6 π cm 2
- C216 π cm 2
- D0 . 216 π cm 2
Correct answer
A. 2 . 16 π cm 2
Step-by-step solution
Let r be the radius of sphere & ∆ r be the error in measuring the radius. Then r = 9   &   ∆ r = 0 . 03 Now, the surface area of sphere is given by, S = 4 π r 2 ⇒ ∆ S = 8 π r ∆ r ⇒ ∆ S = 8 π × 9 × 0 . 03 = 2 . 16 π   cm 2