The curved surface area (CSA) of a cylinder is given by the formula:
CSA=2πrh\text{CSA}=2\pi rhCSA=2πrh
where rrr is the radius and hhh is the height of the cylinder. If the radius is increased to twice its original value (r′=2rr'=2rr′=2r) and the height is reduced to half its original value (h′=h2h'=\frac{h}{2}h′=2h), the new curved surface area becomes:
CSA′=2π(2r)(h2)=2πrh\text{CSA}'=2\pi (2r)\left(\frac{h}{2}\right)=2\pi rhCSA′=2π(2r)(2h)=2πrh
This is exactly the same as the original curved surface area. Conclusion: The curved surface area of the cylinder remains unchanged when the radius is doubled and the height is halved