e^{it} would get replaced with \frac{1+it}{1-it}. t=n/d then implies \frac{1+it}{1-it}=\frac{d+in}{d-in}. RT boils down to doing trigonometry with dot products

e^{it} would get replaced with \frac{1+it}{1-it}. t=n/d then implies \frac{1+it}{1-it}=\frac{d+in}{d-in}. RT boils down to doing trigonometry with dot products and without square roots. There's a temptation to replace dot products with ordinary trigonometry, but RT says don't do it because it's a step back.