Question

The dot product of two vectors is equal to zero then the angle b/w the vectors is?
(a)0
(b)180
(c)90
(d) 160

Answer 1

90 degrees.....as cos90=0......eg:
a.b=abcos(theta)
where a and b are the magnitudes of a and b vectorsand theta is the angle between them. The dot product between 2 mutually perpendicular vectors is 0 as cos 90=0

Answer 2

then the angle b'w them is 90?

Answer 3

It must be equal to 90º

Answer 4

See here http://www.mathsisfun.com/algebra/vectors-dot-product.html