cosθ = (a · b)/(|a| |b|)= [(4)(- 1) + (3)(2)]/[√(4² + 3²) · √(1² + 2²)] = 2/(5√5)θ = 79.695°a - λb = (4i + 3j) - λ(- i + 2j) = (4 + λ)i + (3 - 2λ)j2a + b = 2(4i + 3j) +...