JEE Main2012MathematicsStraight LinesActual
A line is drawn through the point (1,2) to meet the coordinate axes at P and Q such that it forms a triangle OPQ , where O is the origin. If the area of the triangle OPQ is least, then the slope of the line PQ is
Options
- A- 1 4
- B-4
- C-2
- D- 1 2
Correct answer
C. -2
Step-by-step solution
Equation of line passing through (1,2) with slope m is y-2=m(x-1) Area of OPQ = (m-2)^2 2|m| = m^2+4-4 m 2 m = m 2 + 2 m -2 is least if m 2 = 2 m m^2=4 m= 2 m=-2