1. Tentukan cos a sudut yang terbentuk oleh pasangan vektor berikut:
a) ū= (1,2) Dan v= (-8,6)
1. a) u.v = 1(-8) + 2.6
= -8 + 12
= 4
[tex] |u| = \sqrt{1 {}^{2} + 2 {}^{2} } \\ = \sqrt{1 + 4} \\ = \sqrt{5} \\ |v| = \sqrt{( - 8) {}^{2} + 6 {}^{2} } \\ = \sqrt{64 + 36} \\ = \sqrt{100} \\ = 10 \\ cos \: \alpha = \frac{u.v}{ |u| \: |v| } \\ = \frac{4}{\sqrt{5} .10} \\ = \frac{2}{5 \sqrt{5} } . \frac{ \sqrt{5} }{ \sqrt{5} } \\ = \frac{2}{5.5} \sqrt{5} \\ = \frac{2}{25} \sqrt{5} [/tex]
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