Answer: 1:1
Step-by-step explanation:
Let r be the radius and h be the height of a cylinder.
Formula: Curved surface area of cylinder = [tex]2\pi rh[/tex]
Now, if radius of a cylinder is doubled and its height is halved, then new radius will be R= 2r and new height will be [tex]H=\dfrac{1}{2}[/tex]
Now, new surface area = [tex]2\pi RH= 2\pi(2r)\dfrac{h}{2}= 2\pi rh[/tex]
Ratio of curved surface areas : [tex]\dfrac{\text{Surface area}}{\text{New surface area}}=\dfrac{2\pi rh}{2\pi rh}=\dfrac{1}{1}[/tex]
Hence, the ratios of their surface areas = 1:1 .
