Question

найдите угол между векторами а (-1;3) б( 4;1)

Answer 1

Cos(a ^ b) = (x1x2 + y1y2)/(√x1² + y1²)(√x2² + y2²)
cos(a ^ b) = (-1•4 + 3•1)/(√1 + 16)(√9 + 1) = -1/√17•10 = - √170/170 ≈ - 0,0767
arccos(a ^ b) = (180° - 89° 25') = 90°35'.