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Class 12 Three Dimensional Geometry · Assertion Reason1 Marksangles_between_lines

Class 12 Maths · Three Dimensional Geometry · Assertion Reason #24

Assertion (A): The oriented unit vectors (−√3/4,1/4,−√3/2) and (−√3/4,1/4,√3/2) make an angle 120°. Reason (R): For unit vectors u,v, cos θ=u·v.

✅ Step-by-Step Solution

Final Answer: Option (A): Both A and R are true, and R correctly explains A.
  1. Both norms are 1 and the dot product is 3/16+1/16−3/4=−1/2; the oriented-vector angle is 120°.

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