If | a | = 3, | b | = 4 and | a $$-$$ b | = 5, then what is the value of | a + b | ?

Let a, b and c be three mutually perpendicular vectors each of unit magnitude. If

A = a + b + c, b = a $$-$$ b + c and C = a $$-$$ b $$-$$ c, then which one of the following is correct?

What is (a $$-$$ b) $$\times$$ (a + b) equal to ?

A spacecraft located at $$\widehat i + 2\widehat j + 3\widehat k$$ is subjected to a force $$\lambda \widehat k$$ by firing a rocket. The spacecraft is subjected to a moment of magnitude