a(-3; 0)
b(-2; 2)
1)|a| = √(-3)²+0² = 3
|b| = √(-2)²+2² = 2√2
2)a•b = |a|•|b|•cosß
cosß = a•b/|a|•|b| = -3•(-2)+0•2/6√2 = 6/6√2 = 1/√2
ß = 45°
