sir,

the dot product of two vectors(having mag and directn) comes out to be a scalar.

(vector)a.(vector)b=ab cos thita

the direction is lost.

How? Why is so?can u explain me with a practical example?

u r trying to understand it in back direction.

it is actually by considering practical things  ,phenomenons logics that these so called formulas n names and properties r formed.

see the example of force.

parallel component of force to the movement causes work. we see that force and displacement r vetors as we need to tell in what direction they r acting.

bt work is a quantity to measure used strength or entity to check the amount used. it has no relation with direction. just we say " itna kaam hua...."

thus w= f.s   n INCLUDES COSQ as this cos gives component of force parallel to s.

thats it.............

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