JEE Advance - Mathematics (1999 - No. 11)
Let $$a$$ and $$b$$ two non-collinear unit vectors. If $$u = a - \left( {a\,.\,b} \right)\,b$$ and $$v = a \times b,$$ then $$\left| v \right|$$ is
$$\left| u \right|$$
$$\,\left| u \right| + \left| {u\,.\,a} \right|$$
$$\,\left| u \right| + \left| {u\,.\,b} \right|$$
$$\left| u \right| + u.\left( {a + b} \right)$$