Explain Solution R.D.Sharma Class 12 Chapter 23 Scalar or Dot Products Exercise 23.1 Question 42 Maths Textbook Solution.
Answer: Proved
Hint: You must know the rules of solving vectors.
Given: If  are three non-coplanar vectors, such that 
 then show that 
 is the null vector.
Solution:
Given that 
So, either or 
Similarly, 
So,  or 
Also, 
So,  or 
But  cannot be perpendicular to 
 as
 are non-coplanar
So, ,
 is null vector.