Question

Даны векторы m ⃗(-4;3) ; n ⃗(5;12)

Найдите cos(mn) ̂

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Answer 1

$\overline{m}=(-4,3)\ \ ,\ \ \overline{n}=(5,12)\\\\a)\ \ cos\alpha =\dfrac{\overline{m}\cdot \overline{n}}{|\overline{m}|\cdot |\overline{n}|}=\dfrac{-4\cdot 5+3\cdot 12}{\sqrt{16+9}\cdot \sqrt{25+144}}=\dfrac{16}{5\cdot 13}=\dfrac{16}{65}$