A straight line L through the point ( 3 ,   - 2 ) is inclined at an angle of 60 ° to the line 3 x…

A straight line L through the point (3, -2) is inclined at an angle of 60° to the line 3x+y=1. If L also intersects the X-axis, then the equation of L is:
  1. y+3 x+2-33=0
  2. 3 y-x+3+23=0
  3. 3 y+x-3+23=0
  4. y-3x+2+33=0

Solution

Let m be the slope of the line,

then tan60o=m+31-m3

3=m+31-3 m

±3=m+31-3 m

3-3m=m+3 or -3+3m=m+3

4m=0 or 2m=23

m=0 or m=3

Since L intersects X-axis we take m=3

and get y=3x+c

Since it passes through 3,-2, therefore line will become  y-3x+2+33=0

Asked in: JEE Main 2015 (11 Apr Online)

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