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Class 12 Three Dimensional Geometry · Assertion Reason1 Marksdirection_cosines

Class 12 Maths · Three Dimensional Geometry · Assertion Reason #25

Assertion (A): The positive z-axis has direction cosines (0,0,1). Reason (R): Direction cosines satisfy l²+m²+n²=1.

✅ Step-by-Step Solution

Final Answer: Option (B): Both A and R are true, but R does not correctly explain A.
  1. The assertion follows from axis angles 90°,90°,0°. The identity alone does not determine the selected direction.

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