Let a→,b→ and c→  be unit vectors such that  a→+b→−c→=0 If the area of triangle formed by vectors  a→ and b→  is A, then what is the value of 4A2?

Given  a→+b→ = c→Now vector c→ is along the diagonal of the parallelogram which has adjacent side vectors  a→ and b→Since c→ is also a unit vector, triangle formed by  vectors  a→ and b→ is an equilateral triangle. Then