Straight Line and Pair of Straight Lines 1 Question 11

11. If the straight line, 2x3y+17=0 is perpendicular to the line passing through the points (7,17) and (15,β), then β equals

(2019 Main, 12 Jan I)

(a) 353

(b) -5

(c) 353

(d) 5

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Solution:

  1. Slope of the line 2x3y+17=0 is

23=m1, (let) and the slope of line joining the points (7,17)

and (15,β) is β17157=β178=m2 (let)

According to the question, m1m2=1

23×β178=1β17=12β=5.



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