A square with an area of 64 in^2 is rotated to form a cylinder. What is the volume of the cylinder? Round to the nearest tenth.(You do not need to include units

Question

Please help me 

Answer 1

Since the area of the suare is 64 in²

The square is 8 by 8 inches

 

When rolled to a cylinder the height will

be 8 inches.

The circumference c = 2πr of the circular tube is

also 8 inches

2πr = 8

r = 8/2π = 4/π

 

Volume = πr²h

= π(4/π)²(8)

= 16(8)/π

= 128/π

= 40.7 in^3

 

Answer 2

We have a 8in by 8in square.  If we take this square and rotate at a fixed point, it forms a radius of 8 in.  Note that the side of the square is the same as the radius of the cylinder.

 

Volume of cylinder = π(8)²(8)

                            = 8³π