Question

Помогите сделать упражнение №14 :(

Answer 1

a¬ {1,2,3} , b¬ {6,4,2}

cosα = $\frac{x1*x2+y1*y2+z1*z2}{\sqrt{x1+y1+z1}*\sqrt{x2+y2+z2} } = \frac{1*6+2*4+3*2}{\sqrt{1+2+3}*\sqrt{6+4+2} } = \frac{6+8+6}{\sqrt{6}*\sqrt{12} } = \frac{20}{\sqrt{72}} = \frac{20\sqrt{72} }{72} =\frac{10\sqrt{72} }{36} =\frac{5\sqrt{72}}{18} = \frac{5*6\sqrt{2} }{18} = \frac{5\sqrt{2} }{3}$