Question

Can someone help me pls

Answer 1

3 cm

Explanation:

• 
  `V_(cylinder) = 189\pi \: cm^3` (Given)

• 
  `h_(cylinder) = 21\: cm` (Given)

• Formula for
  `V_(cylinder)` is given as:

• 
  `V_(cylinder) = \pi r^2h`

• 
  `\implies 189\pi = \pi r^2(21)`

• 
  `\implies ( 189\pi)/(21\pi) = r^2`

• 
  `\implies 9 = r^2`

• 
  `\implies \pm\sqrt 9 = r`

• 
  `\implies \pm 3 = r`

• Length of radius can not negative

• 
  `\implies r = 3 \: cm`

Hope it helps you in your learning process.