In the book COORDINATE GEOMETRY of THREE DIMENSIONS' (1937) of

Robert J.T. Bell there is a statement (EX.1. p. 178) that

the primary semi-axes a[1], a[2] and a[3] of the confocals of

x^2/a^2 + y^2/b^2 + z*2/z^2 = 1through a point (alpha, beta, gamma) satisfy

the equations

alpha^2 = (a[1]*a[2]*a[3])^2/(b^2-a^2)/(c^2-a^2)

beta^2 = - (b^2-a^2+a[1]^2)*(b^2-a^2+a[2]^2)*(b^2-a^2+a[3]^2)//(a^2-b^2)/(c^2-b^2)

gamma^2 = (c^2-a^2+a[1]^2)*(c^2-a^2+a[2]^2)*(c^2-a^2+a[3]^2)//(b^2-c^2)/(a^2-c^2)

I'm trying to solve these equations for a[1], a[2] , a[3] and check the result by substituting it in the above equations by computer. The first and second equations give fine results. However, the third does not. Perhaps an error? Of course, probably I made an error

Perhaps there is a fool like me wasting his time the way I do.

Nevertheless, your comment will be appreciated.

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