Scalar dot product

Calculate u.v if |u| = 5, |v| = 2 and when angle between the vectors u, v is:

a) 60°
b) 45°
c) 120°

Correct answer:

a =  5
b =  7.0711
c =  -5

Step-by-step explanation:

u=5 v=2 α=60 °  a=u v cosα°=u v cos60° =5 2 cos60° =5 2 0.5=5=5
β=45 °  b=u v cosβ°=u v cos45° =5 2 cos45° =5 2 0.707107=7.071=7.0711
γ=120 °  c=u v cosγ°=u v cos120° =5 2 cos120° =5 2 (0.5)=5=5



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