Розділ 3. КООРДИНАТИ І ВЕКТОРИ » 14.22

(c ̅,d ̅) = 60°; |c ⃗| = 1; |d ⃗| = 2. Знайдіть: (c ⃗,d ⃗) = 60°; |c ⃗| = 1, |d ⃗| = 2. 1) c ⃗ d ⃗ = 1 • 2 • cos60° = 2 • 1/2 = 1. 2) c ⃗ (c ⃗ – d ⃗) = c ⃗2 – c ⃗ • d ⃗ = 12 – 1 = 0. 3) d ⃗(c ⃗ + d ⃗) = d ̅c ̅ + d ̅2 = 1 + 22 = 5. 4) d ⃗(2c ⃗ – 3d ⃗) = 2d ⃗ • c ⃗ – 3d ⃗2 = 2 • 1 – 3 • 4 = 2 – 3 • 4 = –10.