Most Important Selected Qs for JEE AdvancedMathematicsStraight Lines
Paragraph: Through point O a straight line L₁ is drawn to cut two given straight lines 3 x+4 y-5=0 and x+2 y-3=0 at the points L & M , where O is origin. On the basis of above information answer the following : Question: The equation of line L₁ if O L: O M is equal to 5: 3 is -
Options
- Ax+2 y=0
- B2 x-y=0
- Cx+y=0
- Dx-y=0
Correct answer
C. x+y=0
Step-by-step solution
Let equation of straight line through O is x = y =r Let OL = r ₁ and OM = r ₂ , then the coordinates of L and M are given by L ( r ₁ , r ₁ ) and m ( r ₂ , r ₂ ) . Let N(h, k) be the variable point such that O N=r₃ , then h=r₃ , k=r₃ , since L and M lie on 3 x+4 y-5=0 and x+2 y-3=0 so r₁(3 +4 )=5 and r₂( +2 )=3 r ₁ r ₃ = 5 3 ~h +4 k and r ₂ r ₃ = 3 ~h +2 k aligned & Now r₁ r₂ = 5 3 & 5 (3 +4 ) ( +2 ) 3 = 5 3 & +2 =3 +4 & 2 +2 =0 =-1 & equation of L₁ will be x+y=0 aligned