The angle between the planes \(2x + y + 3z - 2 = 0\) and \(x - 2y + 5 = 0\) is :
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 90°
The angle between two planes is the angle between their normals:
\(\vec{n}_1 = 2\hat{\imath} + \hat{\jmath} + 3\hat{k}\)
\(\vec{n}_2 = \hat{\imath} - 2\hat{\jmath} + 0\hat{k}\)
\(\vec{n}_1 \cdot \vec{n}_2 = 2(1) + 1(-2) + 3(0) = 0\)
The dot product is 0, so the normals are perpendicular, and
\(\theta = 90^\circ\)
Note: This topic was not in the CUET 2026 syllabus.