Force and motion
Force and Motion
Pop-ups that Lie Flat
Why A + D = B + C
A + D on the book is the same length as B + C on the pop-up
What it looks like from an edge view
A = C and B = D, so it …
a) … looks like a parallelogram when book is 3/4 open.
b) … looks like a rectangle when book is 1/2 open
c) … looks like a parallelogram when book is 1/4 open