Unit vector in direction of B=5i-7k, w/ A=3i-2j

[shivers20]

Please check my work.

A=3i-2j, B=5i-7k and u is a unit vector in the direction of vector B.

(a) A . B= 15

(b) I have picture of an empty rectangle, what does this mean?

(c) |B| = sqrt[74]

(d) A x A= 10i-21j+10k

(e) u= ?

 

[pka]

Your parts a & c are correct.
I too have no idea what part b could mean.
Any vector crossed with itself is 0: AxA=0.
Now $\displaystyle u = \frac{b}{{\left\| b \right\|}}$