See mathstodon.xyz/@unknown/101273 for a festive two-to-one star dissection. Merry Christmas, everyone, or whatever your appropriate seasonal greeting might be!

Many thanks for introducing!

By the way, in some cases it may be more suitable the another method…

Although, Dudeney's method is nice. I call that name of this attached is "Santa Transform". Thank God It's !

Although, "Puzzdog's dissection" method is suitable for converting parallelograms at equal angles (cf. Attached image is a method of combining similar triangles (It is described in the book of 細矢治夫ら著『多角形百科』 amazon.co.jp/dp/4621089404/
.).). I used the method to mathstodon.xyz/@unknown/101280

A Mastodon instance for maths people. The kind of people who make $$\pi z^2 \times a$$ jokes. Use $$ and $$ for inline LaTeX, and $ and $ for display mode.