Hello, GAdams!
When you cut a piece of A4 paper in half (portrait, cut across)
you get two pieces of A5 paper.
A5 paper is similar to A4 paper.
Express the length of A5 paper as a percentage of the length of A4 paper.
Another approach (to me, the obvious one) . . . make a sketch! Code:
- *-----------* -
: | | :
: | | ½L
: | | :
L * - - - - - * -
: | | :
: | | ½L
: | | :
- *-----------* -
: W :
A4 has length , width .
A5 has length , width .
We want the ratio: .
Since the rectangles are similar: .
Hence: .
Therefore: is about 70.7% of .