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Can anybody explain if the reciprocal cone of the cone touching the three axes will be the cone touching the three coordinate planes. If yes, why?

$3$-D diagram would really help if possible. Thanks.

Ng Chung Tak
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1 Answers1

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It turned out that the reciprocal cone is just what you get taking the inverse of the symmetric matrix that defined the first cone. I gave a big answer at condition for cones to be reciprocal

I'm not going to post any diagrams.

The "cone touching the three axes" is $$ yz + zx + xy = 0. $$ The matrix can be the Hessian matrix of second partial derivatives of the quadratic form. The basic rule is that the Hessian matrix have determinant not equal to zero.

Will Jagy
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