Showing that the distributive law holds in twizzle arithmetic is equivalent to proving the trigonometric addition formulae.


r1 cis(q1) ×r2 cis(q2)
=
r1r2 cis(q1+q2)
=
r1r2(cosq1 + i sinq1)(cosq2 + isinq2)
=
r1r2((cosq1cosq2-sinq1sinq2) + i(sinq1cosq2+cosq1cosq2))
That's not the focus of this question though. What we're really looking for is some experimentation with the animation leading to an understanding of the behaviour of (z-i) , (z+i) , and (z-i)(z+i) as z moves in a loop-like path.

It's quite useful to look at the case where the beige a -twizzle is zero in the second animation.