the height of a right circle cine is 4cm. the radius of its base is 3cm. find its curved surface area.?
"right circle cine" ----> right-circular cone ??
You have a right-angled triangle with base of 3 and height of 4
Find the hypotenuse. (you should recognize that triangle)
You want only the curved surface area, not the circular base, so
SA = πrL, where L is what you found for your hypotenuse.
Go for it!