Question

Дан вектор m(-3, 0) и n(-2, 2). Найдите угол между векторами m и n.

Answer 1

$cos( alpha ) = frac{m times n}{ |m| times |n| }$
m*n = -3*(-2)+0*2 = 6
|m| = sqrt ((-3)^2+0^2) = 3
|b| = sqrt ((-2)^2+2^2) = sqrt (8) = 2sqrt (2)
$cos( alpha ) = frac{6}{3 times 2 sqrt{2} } = frac{1}{ sqrt{2} } = frac{ sqrt{2} }{2}$
a = 45°.