SAT cylinder problem

[Guest]

6. Points A and B are on the top and bottom edges of a cylindrical roll of paper of height 8 and circumference 12. A and B are diagonally opposite each other. The paper is cut along line C and opened out. How far apart are A and B on the flat surface?

I'm not sure how they found the diameter to equal 6 if C=12
Please help if you can.

[Guest]

A wee diagram would help.....
I assume C is a line from A to B around the roll....as in a spiral....
A and B are diagonally opposite so half way round so if circumference is 12 then they are 6 apart as looked at round the circumference of the roll.
When you cut along the line C from A to B you end up with a right angled triangle of 6 on one side and 8 on the other (8 is the height of the roll)

On the flat Distance from A to B will be the length of the hypotenuse of this triangle.

that is......squareroot of 6 squared plus 8 squared

equals squareroot of 36 + 64
equals squareroot of 100

equals..... 10 ........

Simple