If a line L is perpendicular to the line 5 x - y = 1 , and the area of the triangle formed by the line L and…

If a line L is perpendicular to the line 5x-y=1, and the area of the triangle formed by the line L and the coordinate axes is 5 sq units, then the distance of the line L from the line x+5y=0 is 
  1. 7 1 3  units
  2. 7 5  units
  3. 5 1 3  units
  4. 5 7  units

Solution

The equation of a line perpendicular to the line ax+by+c=0 is bx-ay+k=0, kR.

Given, line L is perpendicular to 5x-y=1, hence the equation of L is x+5y+k=0

For finding x-Intercept, put y=0

x+k=0,   x=-k

 x-intercept=-k

Similarly, for finding y- Intercept, put x=0

5y+k=0,  y=-k5

 y-intercept=-k5

Given, the area formed by the line L with the coordinate axes is 5 sq units.

Hence, the area of Δ=12×-k-k5=5

k2=50

k52

Hence, the equation of the line is Lx⁡+5y⁡±52=0

Now, we know that the distance between the parallel lines ax+by+c=0 and ax+by+c1=0 is c-c1a2+b2

Thus, the distance between the lines x+5y=0 and x+5y⁡±52=0 is

d=±52-012+52

d=5226

d=5213×2=513 units.

Asked in: JEE Main 2014 (19 Apr Online)

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