# What is the cross product of <4 , 5 ,-9 > and <4, 1 ,-2 >?

The cross product of two vectors, $\left(a , b , c\right)$ and $\left(d , e , f\right)$, is given by: $\left(b f - c e , c d - a f , a e - b d\right)$. In this case the solution is $< - 1 , - 28 , - 16 >$.
$< 4 , 5 , - 9 > \times < 4 , 1 , - 2 >$
= <( 5.(-2)-(-9).1, (-9).4-4.(-2), 4.1-5.4 >
= $< - 1 , - 28 , - 16 >$