JEE Main2005MathematicsThree Dimensional GeometryActual
Let a, b and c be distinct non-negative numbers. If the vectors a i +a j +c k , i + k and c i +c j +b k lie in a plane, then c is
Options
- Athe Geometric Mean of a and b
- Bthe Arithmetic Mean of a and b
- Cequal to zero
- Dthe Harmonic Mean of a and b
Correct answer
A. the Geometric Mean of a and b
Step-by-step solution
Vector a i +a j +c k , i + k and c i +c j +b k are coplanar aligned & | array lll a & a & c 1 & 0 & 1 c & c & b array |=0 c^2=a b & a, b, c are in G.P. aligned