θunit length⟨a, b⟩ = |a| |b| cos θ = a1 b1 + a2 b2 = 0.699a = (0.548, 1.05)|a|   = 1.182b = (1.14, 0.0703)|b|   = 1.144θ = 1.03cos θ = 0.517aaxaybbxbystart