The diection cosines of two lines are proportional to `(2,3,-6) and (3,-4,5),` then the acute angle between them is (A) `cos^-1{49/36}` (B) `cos^-1 {(18sqrt(2))/35}` (C) `96^0` (D) `cos^-1(18/35)`

The angle between the plane 2x-y+z=6 nand x+y+2z=3 is (A) pi/3 (B) cos^-1 1/6 (C) pi/4 (D) pi/6

The angle between two planes x+2y+2z=3 and -5x+3y+4z=9 is (A) cos^-1(3sqrt(2))/10 (B) cos^-1 (19sqrt(2))/30 (C) cos^-1 (9sqrt(2))/20 (D) cos^-1 (3sqrt(2))/5

If veca and vecb are two unit vectors such that veca+2vecb and 5veca-4vecb are perpendicular to each other then the angle between veca and vecb is (A) 45^0 (B) 60^0 (C) cos^-1(1/3) (D) cos^-1(2/7)

If veca=(3,1) and vecb=(1,2) represent the sides of a parallelogram then the angle theta between the diagonals of the paralelogram is given by (A) theta=cos^-1(1/sqrt(5)) (B) theta=cos^-1(2/sqrt(5)) (C) theta=cos^-1 (1/(2sqrt(5))) (D) theta = pi/2

The direction cosines of a vector a are cos alpha = 4/(5sqrt(2)), cos beta =1/sqrt(2) and cos gamma =3/(5sqrt(2)) then the vector vecA is

Find the projection of the line segment joining (2,-1,3) and (4, 2, 5) on a line which makes equal acute angles with co-ordinate axes.

the value of cos^-1sqrt(2/3)-cos^-1 ((sqrt6+1)/(2sqrt3)) is equal to:

Find the acute angle between the lines whose direction ratios are proportional to 2:3:6 and 1:2: 2.

If A,B,C,D are (2,3,-1),(3,5,-3),(1,2,3),(3,5,7) respectively, then the angel between AB and CD, is

Find acute angles A and B when 2 sin (A+ B) = sqrt3 and 2 cos (A-B) = sqrt3