Question

https://session.masteringphysics.com/problemAsset/1332409/2/yf_Figure_1_29.jpg

Find the magnitude of B⃗ ×A⃗ .

Answer 1

the cross product is defined

\[\vec X \times \vec Y = |\vec X||\vec Y| \sin \theta \ \hat n\]

so it's "magnitude" is :
\(\|\vec X||\vec Y| \sin \theta \)

you have the length of these vectors and you can work out the angle \(\theta\) between them so plug it all in...

:p