θ
unit length
⟨a, b⟩ = |a| |b| cos θ = a1 b1 + a2 b2 = 0.892
a = (0.437, 0.870)
|a| = 0.9737
b = (1.23, 0.410)
|b| = 1.292
θ = 0.782
cos θ = 0.709
a
ax
ay
b
bx
by
start