(a)
i • i = | i | | i | cos 0° = 1 × 1 × 1 = 1
i • i
= | i | | i | cos 0°
= 1 × 1 × 1
= 1
(b)
j • j = | j | | j | cos 0° = 1 × 1 × 1 = 1
j • j
= | j | | j | cos 0°