Posted by martha on .
ok it asks me 2 find the lateral area of the cylinder ( the radius is 5 n the hight is 5) can some 1 help me with this please
Prinness, I think that 392.5 is pi*r^2*h, or the volume of the cylinder. This question asks for the lateral area.
Lateral area is the area of the side of the cylinder, not of one of the circles at the ends. Picture standing the cylinder on its end like a soup can, and cutting down the side from one end to the other in a vertical line. If you were to remove the ends and flatten out that side of the can, you would get a rectangle with the same height as the original cylinder and a length that is the same as the circumference of one of the ends.
This means that the formula you want to use
is Lateral area = (height)(circumference)
= h * (2*pi*r)