BITSAT2014MathematicsStraight LinesActual
If P₁ and P₂ be the length of perpendiculars from the origin upon the straight lines x +y cosec =a and x -y =a 2 respectively, then the value of 4 P ₁²+ P ₂²
Options
- Aa²
- B2 a²
- Ca² / 2
- D3 a²
Correct answer
A. a²
Step-by-step solution
We have P₁= length of perpendicular from (0,0) on x +y cosec =a aligned i.e. P₁ &= | a ² + e c² |=|a | &= | a 2 2 | or 2 P₁=|a 2 | aligned P ₂= Length of the perpendicular from (0,0) on x -y =a 2 ₂= | a 2 ² + ² |=|a 2 | Now, 4 P₁²+P₂²=a² ² 2 +a² ² 2 =a²