Given the following two vectors in R3:
calculate the cross product X × Y
X = 6i - 3j + 6k
Y = 8i + 2j - 9k
i | j | k |
x1 | x2 | x3 |
y1 | y2 | y3 |
→ |
i | j | k |
6 | -3 | 6 |
8 | 2 | -9 |
X × Y = (x2y3 - x3y2)i + (x3y1 - x1y3)j + (x1y2 - x2y1)k
X × Y = (-3 x -9 - 6 x 2)i + (6 x 8 - 6 x -9)j + (6 x 2 - -3 x 8)k
X × Y = (27 - 12)i + (48 - -54)j + (12 - -24)k
X × Y = 15i + 102j + 36k
Since X × Y <> 0:
X and Y are not parallel