The number of distinct real values of , for which the vectors , and are coplanar, is
- (A)zero
- (B)one
- (C)two✓ Correct
- (D)three
Answer: (C)
Solution
Vectors are coplanar if their scalar triple product is zero:
Expanding:
Factoring:
Since for all real , we have , giving .
Therefore, there are two distinct real values.
Expanding:
Factoring:
Since for all real , we have , giving .
Therefore, there are two distinct real values.
JEE Advanced · 2007 · 08 Apr 2007 · Paper 1 · Single correct option