Straight Line and Pair of Straight Lines 1 Question 44

44. Let the algebraic sum of the perpendicular distance from the points (2,0),(0,2) and (1,1) to a variable straight line be zero, then the line passes through a fixed point whose coordinates are… .

(1991, 2M)

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Solution:

  1. Let the variable straight line be ax+by+c=0

where, algebraic sum of perpendiculars from (2,0),(0,2) and (1,1) is zero.

2a+0+ca2+b2+0+2b+ca2+b2+a+b+ca2+b2=03a+3b+3c=0a+b+c=0

From Eqs. (i) and (ii) ax+by+c=0 always passes through a fixed point (1,1).



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