2020 · Q45
If radius of a sphere is rational, then which of the following is/are correct?
- 1Its surface area is rational.
- 2Its volume is rational.
Select the correct answer using the code given below:
Elementary MathematicsMensuration
- A1 only
- B2 only
- CBoth 1 and 2
- DNeither 1 nor 2
Explanation
Surface area 4*pi*r^2 and volume (4/3)*pi*r^3 both contain pi, so both are irrational whenever r is rational (and nonzero). Neither statement is correct - option (D). For example with r = 1, the surface area 4*pi and the volume 4*pi/3 are both irrational.