Three Dimensional Geometry

Let L1: r=( i- j+2 k)+ ( i- j+2 k), R, L2: r=( j- k)+ (3 i+ j+p k), R, and L3: r= ( i+m j+n k), R be three lines such that L1 is perpendicular to L2 and L3 is perpendicular to both L1 and L2. Then, the point which lies on L3 is

1. (1,7,-4)
2. (1,-7,4)
3. (-1,7,4)
4. (-1,-7,4)

Let a line passing through the point (-1,2,3) intersect the lines L1: x-13= y-22= z+1-2 at M( , , ) and L2: x+2-3= y-2-2= z-14 at N(a, b, c). Then, the value of ( + + )2(a+b+c)2 equals .

Let PQR be a triangle with R(-1,4,2). Suppose M(2,1,2) is the mid point of PQ. The distance of the centroid of from the point of intersection of the lines x-20= y2= z+3-1 and x-11= y+3-3= z+11 is

1. 69
2. 99
3. 69
4. 9

A line with direction ratios 2,1,2 meets the lines x=y+2=z and x+2=2y=2z respectively at the points P and Q. If the length of the perpendicular from the point (1,2,12) to the line PQ is l, then l2 is .

Let P(3,2,3), Q(4,6,2) and R(7,3,2) be the vertices of . Then, the angle is

1. -1 ( 718 )
2. 6
3. -1 ( 118 )
4. 3

Let O be the origin, and M and N be the points on the lines x-54= y-41= z-53 and x+812= y+25= z+119 respectively such that MN is the shortest distance between the given lines. Then OM ON is equal to .

The distance of the point (7,-2,11) from the line x-61= y-40= z-83 along the line x-52= y-1-3= z-56, is :

1. 12
2. 18
3. 21
4. 14

If the shortest distance between the lines x-41= y+12= z-3 and x- 2= y+14= z-2-5 is 6 5, then the sum of all possible values of is :

1. 10
2. 5
3. 7
4. 8

Let the position vectors of the vertices A, B and C of a triangle be 2 i+2 j+ k, i+2 j+2 k and 2 i+ j+2 k respectively. Let l1, l2 and l3 be the lengths of perpendiculars drawn from the orthocentre of the triangle on the sides AB, BC and CA respectively, then l12+l22+l32 equals:

1. 14
2. 15
3. 13
4. 12

Let the image of the point (1,0,7) in the line x1= y-12= z-23 be the point ( , , ). Then which one of the following points lies on the line passing through ( , , ) and making angles 2 3 and 3 4 with y-axis and z-axis respectively and an acute angle with x-axis ?

1. (1,-2,1+ 2 )
2. (3,-4,3+2 2 )
3. (3,4,3-2 2 )
4. (1,2,1- 2 )