A field is given as \mathbf{G}=\frac{25}{x^{2}+y^{2}}\left(x \mathbf{a}_{x}+y \mathbf{a}_{y}\right). Find: (a) a unit vector in the direction of \mathbf{G} at P(3,4,-2) ;(b) the angle between \mathbf{G} and \mathbf{a}_{x} at P ;\text{(c)} the value of the double integral \int_{x=0}^{4} \int_{z=0}^{2} \mathbf{G} \cdot d x d z \mathbf{a}_{y} on the plane y=7.
no plano y=7.
Vamos, respectivamente, avaliar \mathbf{G} em P, usar a definição de ângulo entre vetores e interpretar o elemento de área vetorial no plano y= constante.