Angle between two planes
Three-dimensional geometry and vector algebra · Mathematics
Study notes
Q: Find the angle between x + 2y + 2z = 5 and 2x − y + 2z = 3. n₁ = (1,2,2), n₂ = (2,−1,2). n₁·n₂ = 2−2+4 = 4. |n₁| = 3, |n₂| = 3. cosθ = 4/9. θ ≈ 63.6°.