every formula_1-sided zonogon can be tiled by formula_2 four-sided zonogons. in this tiling, there is one four-sided zonogon for each pair of slopes of sides in the formula_1-sided zonogon. at least three of the zonogon's vertices must be vertices of only one of the four-sided zonogons in any such tiling. for instance, the regular octagon can be tiled by two squares and four 45° rhombi.