In
the figure bellow, ABCD is a square and the measure of the angle EAF is 45
degrees (E and F lie on BD). If S_{1}, S_{2}, and S are the areas of the squares of diagonals BE,
FD, and EF, respectively, prove that S = S_{1} + S_{2}.

#Geometry Problem 1338: Four Squares, Diagonals, Angle, 45 Degrees, Areas, #Typography #iPad Apps https://t.co/R6XhdwsOgs #geometricart #fractals #sketch #drawing #proof #math #highschool pic.twitter.com/eqZYFwx9ZO

— Antonio Gutierrez (@gogeometry) February 27, 2018

See also:

Art of problem 1338

Typography of problem 1338

Art of problem 1338: Hyperbolic Kaleidoscope

Art of problem 1338: Deform around a spiral.