Straight Line and Pair of Straight Lines 2 Question 6

6. The area of the triangle formed by the intersection of line parallel to X-axis and passing through (h,k) with the lines y=x and x+y=2 is 4h2. Find the locus of point P.

(2005)

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Answer:

Correct Answer: 6. 2x=±(y1)

Solution:

  1. Here, the triangle formed by a line parallel to X-axis passing through P(h,k) and the straight line y=x and y=2x could be as shown below:

Since, area of ABC=4h2

12ABAC=4h2

where, AB=2|k1| and AC=2(|k1|)

122(k1)2=4h24h2=(k1)22h=±(k1)

The locus of a point is 2x=±(y1).



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