Question

If (a×b) points along negative z-axis, then the vectors a and b must lie in (a) .zx-plane (b) .yx-plane (c) .xy-plane (d) None of the above

Answer 1

Ans (b) YX Plane

Use right hand rule to find the direction of cross product

Answer 2

Given that,

Vector (a×b) points along negative z-axis.

To find,

The vectors a and b are lie in which plane?

Solution,

To find the direction of cross product, ring hand rule is used. In this case, (a×b) points along -z axis, it means it is in the plane containing these two vectors.

Using right hand rule, we find that the vectors a and b must lie in YX plane. Hence, the correct option is (b).