Скалярное произведение векторов \(\displaystyle \overrightarrow {a}\) и \(\displaystyle \overrightarrow {b}\) равно \(\displaystyle -27,\) \(\displaystyle |\overrightarrow {a}|=5,\) \(\displaystyle |\overrightarrow {b}|=6.\)

Найдите косинус угла между векторами \(\displaystyle \overrightarrow {a}\) и \(\displaystyle \overrightarrow {b}.\)

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