JEE Main20258 Apr 2025Evening ShiftMathematicsStraight LinesActual
A line passing through the point P ( a , ) makes an acute angle with the positive x -axis. Let this line be rotated about the point P through an angle 2 in the clock-wise direction. If in the new position, the slope of the line is 2- 3 and its distance from the origin is 1 2 , then the value of 3 a^2 ^2 -2 3 is
Options
- A4
- B6
- C5
- D8
Correct answer
A. 4
Step-by-step solution
aligned & m _ PR =2- 3 = 15^ & 2 =15^ =30^ aligned equation of PR : aligned & y= 15^ (x-a) & y=(2- 3 )(x-a) aligned distance from origin = 1 2 aligned & | 3 a-2 a 4+3-4 3 +1 |= 1 2 & |a|(2- 3 ) 2 (2- 3 ) = 1 2 & |a|= 2 2- 3 = 2 ( 2+ 3 ) & a^2=2(2+ 3 ) & 3 a^2 ^2 -2 3 & 3 (4+2 3 ) 1 3 -2 3 =4 aligned