Harvard Psychological Studies, Volume 1 / Containing Sixteen Experimental Investigations from the Harvard Psychological Laboratory.

by Unknown

then

arc CA'	=	arc BB'
r		r'

or, omitting the word "arc" and clearing of fractions,

r'(CA') = r(BB').

But now

CA' = BA' - BC,

while

BA' = Z and BC = p;

therefore

CA' = Z-p.