Straight Line Question 248

Question: P is point on the line $ y+2x=1, $ and Q and R are two points on the line $ 3y+6x=6 $ such that triangle PQR is an equilateral triangle. The length of the side of the triangle is

Options:

A) $ 2/\sqrt{15} $

B) $ 3/\sqrt{5} $

C) $ 4/\sqrt{5} $

D) None of these

Show Answer

Answer:

Correct Answer: A

Solution:

  • [a] The given lines are $ y+2x=1 $ and $ y+2x=2. $ The distance between the lines is $ (2-1)/\sqrt{5}=1/\sqrt{5}. $ The side length of the triangle is $ \frac{1}{\sqrt{5}}\cos ec60{}^\circ =\frac{2}{\sqrt{15}}. $