Vector Geometry

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Example 1;

QUESTION 1

find the scalars product of the following pairs of vectors

(a) a= 2i +3j and b= -i +4j

Solution

(a). a.b =2(-1) +3(4)

= -2 +12 =10

QUESTON 2

Find the cosine of angles between the following pairs of vectors

(a) a= 3i -j and b = 5i +2j

Solution

let A be the angle between vectors a and b

/a/ = square root of 9+1= square root 10

/b/ =square root of 25 +4= square root 29

a.b = 3*5+(-1)(2)= 15 - 2

=13

Cos A = a.b

/a/ /b/

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