Use the formulas for the cis you found in Exercise 1 to find a representation of 5i + 6j —...

Use the formulas for the cis you found in Exercise 1 to find a representation of 5i + 6j — (l/2)k in terms of the unit vectors , , and .

Exercise 1

Show that if u, v, and w are mutually perpendicular unit vectors in ℝ3, then for any vector a in ℝ3 there are three numbers c1, c2, and c3 such that a = c1u + c2 v + c3w. (Hint: Think projection.)