12. Let $\mathrm { P } ( \mathrm { a } \sec \mathrm { q } , \mathrm { b } \tan \mathrm { q } )$ and $\mathrm { Q } ( \mathrm { a } \sec \mathrm { q } , \mathrm { b } \tan \mathrm { q } )$ where $\mathrm { q } + \mathrm { q } = \pi / 2$, be two points on the hyperbola $\times 2 / \mathrm { a } 2 - \mathrm { y } 2 / \mathrm { b } 2 =$ 1. If ( $\mathrm { h } , \mathrm { k }$ ) is the point of intersection of the normals at P and Q , then K is equal to : (A) $( a 2 + b 2 ) / a$ (B) $- ( ( a 2 + b 2 ) / a )$ (C) $( a 2 + b 2 ) / b$ (D) $- ( ( a 2 + b 2 ) / b )$
12. Let $\mathrm { P } ( \mathrm { a } \sec \mathrm { q } , \mathrm { b } \tan \mathrm { q } )$ and $\mathrm { Q } ( \mathrm { a } \sec \mathrm { q } , \mathrm { b } \tan \mathrm { q } )$ where $\mathrm { q } + \mathrm { q } = \pi / 2$, be two points on the hyperbola $\times 2 / \mathrm { a } 2 - \mathrm { y } 2 / \mathrm { b } 2 =$ 1. If ( $\mathrm { h } , \mathrm { k }$ ) is the point of intersection of the normals at P and Q , then K is equal to :\\
(A) $( a 2 + b 2 ) / a$\\
(B) $- ( ( a 2 + b 2 ) / a )$\\
(C) $( a 2 + b 2 ) / b$\\
(D) $- ( ( a 2 + b 2 ) / b )$\\