Question

2. Find the value of A in the unit vector 0.4î+ 0.8ĵ+ λk.​

Answer 1

There is no A in the vector, so I assume you mean λ.

The magnitude of any unit vector is 1, so

`\|0.4\,\vec\imath + 0.8\,\vec\jmath + \lambda \,\vec k\| = √(0.4^2 + 0.8^2 + \lambda^2) = 1`

Square both sides and solve.

`0.4^2 + 0.8^2 + \lambda^2 = 1^2 \implies \lambda = \boxed{\pm √(0.2)}`