81,87°
Explicação passo a passo:
[tex]\cos\theta=\dfrac{\vec u \cdot \vec v}{|\vec u |\cdot |\vec v|} \implies\cos\theta=\dfrac{(-7\cdot0)+(-1\cdot(-2))}{\sqrt{(-7)^2+(-1)^2}\sqrt{(0)^2+(-2)^2} } \implies\\\\\implies\cos\theta=\dfrac{2}{10\sqrt{2}}\implies\cos\theta=\dfrac{\sqrt{2}}{10}\implies \theta=\arccos\dfrac{\sqrt{2}}{10}=81,87^{\circ}[/tex]
