AP EAMCET202420 May 2024Morning ShiftMathematicsThree Dimensional GeometryActual
The direction cosines of two lines are connected by the relations l+m-n=0 and l m-2 m n+n l=0 . If is the acute angle between those lines then =
Options
- A6
- B1 7
- C5 6
- D3
Correct answer
B. 1 7
Step-by-step solution
+m-n=0 n= +m m-2 m n+n =0 m-2 m( +m)+ (n+m)=0 ^2-2 m^2=0 =- 2 m, = 2 m n=(1- 2 ) m, n=(1+ 2 ) m : m: n=- 2 : 1:(1- 2 ) or 2 : 1: 1+ 2 Angle between these lines = |( 2 )(- 2 )+(1)(1)+(1- 2 )(1+ 2 )| 2+1+1+2-2 2 2+1+1+2+2 2 = |-2| 6-2 2 6+2 2 = 1 7