Question

The number of vectors of unit length perpendicular to the vectors `vec"a" = 2hat"i" + hat"j" + 2hat"k"` and `vec"b" = hat"j" + hat"k"` is ______.

Options

• One

• Two

• Three

• Infinite

Answer 1

The number of vectors of unit length perpendicular to the vectors `vec"a" = 2hat"i" + hat"j" + 2hat"k"` and `vec"b" = hat"j" + hat"k"` is two.

Explanation:

The number of vectors of unit length perpendicular to vectors `vec"a"` and `vec"b"` os `vec"c"`  ...(Let)

∴ `vec"c" = +-(vec"a" xx vec"b")`

So, there will be two vectors of unit length perpendicular to vectors `vec"a"` and `vec"b"`.