Given the following two vectors in R3:
calculate the cross product X × Y
X = 8i - j + 3k
Y = 5i + j - 9k
i | j | k |
x1 | x2 | x3 |
y1 | y2 | y3 |
→ |
i | j | k |
8 | -1 | 3 |
5 | 1 | -9 |
X × Y = (x2y3 - x3y2)i + (x3y1 - x1y3)j + (x1y2 - x2y1)k
X × Y = (-1 x -9 - 3 x 1)i + (3 x 5 - 8 x -9)j + (8 x 1 - -1 x 5)k
X × Y = (9 - 3)i + (15 - -72)j + (8 - -5)k
X × Y = 6i + 87j + 13k
Since X × Y <> 0:
X and Y are not parallel