The Angle of a Fold
Take a square piece of paper.
Fold one corner so that it touches the centerline.
What angle is x?
75 degrees.
The angle at the bottom right is one angle of an equilateral triangle, and so is 60 degrees.
The white angles are an equal division of 90 – 60, and so are 15 degrees each.
180 – 90 – 15 = 75.
