Straight Line and Pair of Straight Lines 1 Question 45

45. The orthocentre of the triangle formed by the lines x+y=1,2x+3y=6 and 4xy+4=0 lies in quadrant number… .

(1985,2M)

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Solution:

  1. Let H(h,k) be orthocentre.

( slope of AH)( slope of BC)=1

k167h+37(1)=1

k167=h+37hk=197

Also, ( slope of CH)( slope of AB)=1

k4h+3(4)=14k16=h3h+4k=13

On solving Eqs. (i) and (ii), we get h=37,k=227

Orthocentre 37,227

Hence, this coordinate lies in the first quadrant.



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