Question

I need proper steps​

Answer 1

Answer:

(i) 1386

(ii)7

Step-by-step explanation:

(i) When r= 10.1/2

               = 21/2

$S=4\pi r^{2}$

= 4 × 22/7 × 21/2 ×21/2

= 22×3×21

= 1386

(ii) S= 616 ⇒ $616 = 4\pi r^{2}$

r² = $\pi r^{2} = \frac{616}{4} \\ r^{2}= 154. \frac{7}{22} \\ r^{2}=49\\ r=7$