А) 24 * (2 3/4х - 1 5/6х) = 33
2 9/12х - 1 10/12х = 33 : 24
1 21/12х - 1 10/12х = 33/24
11/12х = 11/8
х = 11/8 : 11/12
х = 11/8 * 12/11
х = 12/8 = 3/2 = 1,5
б) 11/12х + 5 5/8 = 10 2/3
11/12х = 10 2/3 - 5 5/8
11/12х = 10 16/24 - 5 15/24
11/12х = 5 1/24
х = 5 1/24 : 11/12
х = 121/24 * 12/11
х = 11/2 = 5 1/2 = 5,5
8-23/7=56/7-23/7=33/7=4цел5/7
71/13-2=71/13-26/13=45/13=3цел6/13
<span>Дано точки А (2;5), В (2 ;7 ), С (1;2), D (3;4). Найти угол между векторами
</span>→ →<span>
АВ и СD.
Решение:
</span>→ → → →<span>
AB{0, 2}, CD{2, 2}, AB* CD = 0*2 + 2*2 = 4
</span>→ →<span>
|AB| = </span>√(0² + 2²) = 2, |CD| = √(2² + 2²) = 2√2
Cosα = 4/4√2 = 1/√2, ⇒α = 45°