AP EAMCET201921 Apr 2019Evening ShiftMathematicsStraight LinesActual
If the perpendicular bisector of the line segment joining A ( α , 3 ) and B ( 2 , - 1 ) has y -intercept 1 , then α =
Options
- A0
- B± 1
- C± 2
- D± 3
Correct answer
C. ± 2
Step-by-step solution
Consider the equation of perpendicular bisector is y = m   x + c The intercept is 1 , thus the equation becomes y = m   x + 1   The mid-point of the points A ( α , 3 ) and B ( 2 , - 1 ) is α + 2 2 , 1 Since the equation passes through α + 2 2 , 1 Thus, 1 = m α + 2 2 + 1 2 = m ( α + 2 ) + 2 m ( α + 2 ) = 0 m α + 2 m = 0   … I Here, m is the gradient of the perpendicular line. m = - α - 2 4 Substitute the value in equation ( I ) . α 2 - α 4 +