Find the angle between vectors (a + b) and (a - b), if a = (2i - j + 3k) and b = (3i + j + 2k).

Question

Find the angle between vectors (a + b) and (a - b), if vectors a = (2i - j + 3k) and b = (3i + j + 2k).

Answer 1

 \(\vec{a} = (\vec{2i} - \vec{j} + \vec{3k})\)

\(\vec{b} = (\vec{3i} + \vec{j} + \vec{2k})\)

⇒ (- 5 + 5) = \(\sqrt{300}\)cosθ 

⇒ cosθ = 0 

⇒ θ = cos^-1(0) = π/2 

θ = π/2