Find the equation of the line perpendicular to y=x and passing at a distance 3sqrt2 from (4,1).

Expert Answers

An illustration of the letter 'A' in a speech bubbles

The equation is perpendicular to the line y = x. The line y = x has a slope 1. As perpendicular lines have slopes which are negative reciprocals the slope of the required line is -1. The equation of the line is x + y + k = 0

The required line passes through a point which is at a distance 3*sqrt 2 from (4,1).

We use the relation for determining the distance d of a point (x1, y1) from the line ax+by +c = 0, which is:

d = |ax1+by1+c|/ sqrt (a^2+b^2)

=> 3*sqrt 2 = | 4 + 1 + k|/sqrt 2

=> 5 + k = 3*2 = 6

=> k = 1

Therefore the equation of the required line is x + y + 1 = 0.

Approved by eNotes Editorial Team
Soaring plane image

We’ll help your grades soar

Start your 48-hour free trial and unlock all the summaries, Q&A, and analyses you need to get better grades now.

  • 30,000+ book summaries
  • 20% study tools discount
  • Ad-free content
  • PDF downloads
  • 300,000+ answers
  • 5-star customer support
Start your 48-Hour Free Trial