Given the following two vectors in R3:
calculate the cross product X × Y

X = 6i - 3j + 6k

Y = 8i + 2j - 9k

Write the coefficients as a matrix

 i  j  k 
 x1  x2  x3 
 y1  y2  y3 
 → 
 i  j  k 
 6  -3  6 
 8  2  -9 

Evaluate Cross Product Formula

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

Parallel Check:

Since X × Y <> 0:
X and Y are not parallel

Final Answer


X × Y = 15i + 102j + 36k
Since X × Y <> 0:
X and Y are not parallel