Q:- The coplanar points A,B,C,D are (2-x,2,2) , (2,2-y,2) ,(2,2,2-z) and (1,1,1) respectively. Then

A. 1/x+1/y+1/z =1

B. x+y+z=1

C. 1/(1-x) +1/(1-y) +1/(1-z) =1

D. None of these

Dear Tapasranjan

this question can be solved easly by using equation of pane passing through 3 points in determinant form

use determinant form of plane passing trough ((2-x,2,2) , (2,2-y,2) ,(2,2,2-z)

and this plane also passes through (1,1,1) so it will satisfy this point also

put it and simplify

now open determenant

1/x  + 1/y  + 1/z =1

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