Question

The dot product of 2 vectors of magnitude 3 and 5 units cannot be 1. -20 2. 16 3. -10 4. 14

Answer 1

Dot product of two Vectors a & b =a.b.Cos(x).

Where a&b are magnotude of vector a and b respectively and x is angle b/w them.

Cos(x)={-1,1}

So Cos(x)=dot product/product of magnitude

So your 1st and 2nd option are wrong as these are not satisfied the range of cosine.

Your answer should be 3rd and 4th as these are correct.