Use the vector u = 6, 6 to find the indicated quantity.

Question

u · u

Answer 1

For vectors v = <a, b> and w = <c, d>, v • w = ac + bd.

So, if u = <6, 6>, then u • u = (6)(6) + (6)(6) = 72.

Answer 2

u · u = ||u|| ||u|| cos θ

What is θ? What is the cosine of θ?